DOES MY CAR NEED A SMOG CHECK?

Smog inspections are generally required during a vehicle's initial registration in California and once, every two years, thereafter. This inspection cycle will continue for as long as the vehicle is registered in this State.

Smog Inspections are also required anytime a vehicle is sold or bought in California. During a title transfer the Department of Motor Vehicles will not allow a vehicle to be registered unless it is presented with a valid smog certificate.
There are special testing procedures for vehicles, which are classified as "Gross Polluters". These include Test Only and State Referee inspections. If your vehicle requires a Test Only or Referee inspection, your DMV paperwork will advise you of it. Prepare your smog check checklist ahead of time. Preparing is the key.

The Smog Check Program applies to 1976 and newer passenger vehicles and trucks powered singly or in combination by:

* Gasoline
* Propane
* Natural gas
* Diesel
* Methanol / Ethanol fuels

1975 & Older - Effective 04/01/05: Under the old law, 1975 and subsequent model year vehicles became exempt from Smog Check when they turned 30 years old. A 1976 model year vehicle was exempt in 2005, a 1977 in 2006, etc.

Under the new law... commenced April 1, 2005, exempt from smog check requirements are any motor vehicle manufactured prior to the 1976 model year. All vehicles 1976 and newer vehicles will be tested according to state emission law. This law repeals the 30-year rolling exemption.

6 Yrs & Newer - Effective 01/01/05: Will expand the model-year smog check exemption to include motor vehicles 6 or less model years old, unless ARB (Air Resource Board) determines that including the 5th and 6th model-year vehicles in the exemption would prohibit the state from meeting the requirements of the federal Clean Air Act.

Exempt: Still exempt from the State of California Smog Check program are:

* Hybrid powered motor vehicles
* 2 wheel motorcycles
* Diesel cars & trucks (1997 & older)
* Diesel trucks (over 14,500 GVW)
* Motor vehicles w/ 1 or 2 cylinders
* 2-stroke engines(excluding rotary)
* Engines under 819cc
* 1975 model year vehicles and older
* 6 model years old (except for initial registration in California or change of ownership)



Miles:
Which Type Should I Choose?



* California smog check program
* Does my car need a smog inspection?
* What is a test only smog inspection?
* What is a gross polluter vehicle?
* My car is out of state and I need a California smog test
* I just moved to California. How do I register my car?
* Roadside emissions test checkpoints

Diesel Cars and Trucks - Effective 01/01/2010: All Diesel vehicles, cars and trucks 1998 and newer, and weighing under 14,500 GVW will need a smog check.
The smog test will not include the emissions test portion of the regular inspection. There will be no tailpipe emissions test.
Instead the Diesel smog check will focus on a visual inspection of your vehicle's emissions/smog components, a system check of the On Board Diagnositics (OBD II) system, a visual smoke check for excessive black smoke, and an EVAP functional test.

Hybrid Vehicles (HEVs) Exempt From Smog Test: A hybrid electric vehicle is defined as any passenger vehicle that uses an electric motor as a part of its propulsion system, as well as an internal combustion engine.

Currently Hybrid-Electric vehicles are exempt from only the initial biennial and change-of-ownership smog test inspections. The emissions performance of HEVs cannot be accurately determined by the current emissions test process. California is developing new testing procedures.

Once these procedures are developed, Hybrid Electric cars and trucks may be required to get tested. Some HEV models are also built as non-hybrids. For example the Tahoe, Camry, Civic, and Escape. Only the hybrid model of these vehicles are exempt from the smog check process.

The following HEV's are exempt from initial "biennial" and "change of ownership" smog inspections until further notice.

* Chevy Hybrid Tahoe – all years
* Honda Insight – all years
* Honda Civic Hybrid – all years
* Lexus Hybrid RX, GS, LS – all years
* Toyota Prius – all years
* Toyota Hybrid Camry – all years
* Toyota Hybrid Highlander – all years

Some currently manufactured HEV's are not designed to allow the internal combustion engine to operate in modes which would allow the loaded or idle type of Smog Check testing. These vehicles currently receive an exemption certificate at the Referee.
The Referee will not perform a Smog Check inspection on these vehicles, but only verify them as hybrids.

BAR and the Department of Motor Vehicles (DMV) have recently automated the exemption process for all HEVs identified to BAR by the manufacturers.
More HEVs will be added to the exemption list as information to identify these vehicles is received by Bureau of Automotive Repair (BAR).

Some owners of newer model HEVs may receive registration renewal notices from the DMV before information to identify them as hybrids are received by the Bureau of Automotive Repair. They should contact a DMV office at (800)777-0133 to complete their registration without a Smog Check certificate.

How to Pass the California Emissions Test. 3-Part Test.

First, let's look at the three sections the California Smog Inspection consists of:

* Emissions Inspection
* The Visual Inspection
* The Functional Inspection

NOTE:

The State of California requires smog stations to test vehicles in the specific order listed above. The first inspection (emissions inspection) is performed by the exhaust gas analyzer "smog machine".
During this step of the smog check inspection, the smog machine is looking for the presence of Hydrocarbons, Carbon Monoxides and Nitrous Oxides in your vehicle's exhaust. These are the three (3) undesired chemicals which are responsible for the production of SMOG. The next two inspections, the visual and functional, will be performed both by the smog technician and/or the smog machine.

In order to pass Califoria's emissions test, your vehicle must produce passing results in all three test section.

Enhanced Smog Test - In parts of California where smog pollution is higher, vehicle owners are now required to complete an "Enhanced" version of California's smog test.

The "Enhanced" smog test requires your vehicle to be driven on a dynamometer while the smog machine collects emissions samples from the tailpipe.
The "Enhanced" smog test has been proven to retrieve a more accurate sample of a vehicle's emissions output, then it's predecessor, the "Basic" smog test. The "Basic" smog test requires vehicles to be tested, only at idle and 2500 rpms. "Basic" smog test vehicles do not need to be driven on a dynomometer.

Basic Smog Test - Counties in California with low smog pollution require the "Basic" smog test. If your county has been added to the "Enhanced" smog test requirement list, the smog stations in your local area will have the neccessary equipment to test your vehicle. No specific action will be required by the vehicle owner.

Change of Ownership - Counties with even less smog pollution are designated as "Change of Ownership" areas. In Change of Ownership parts of the state, smog checks are only required when a vehicle is bought or sold, and when a used vehicle is imported into the state of California.
New vehicles imported into California by the vehicle manufacturer do not need smog checks. These vehicles are California certified during production.

Miles:
Which Type Should I Choose?


* The Entire Emissions Test Process... Step-by-Step

* Part 1. Emissions Inspection
* Part 2. The Visual Inspection
* Part 3. The Functional Tests

HOT TOPICS (updated Jan 2010)

* How to pass the emissions test
* My car failed the emissions test
* Six must do's before you visit the smog center
* Check Engine Light - How to turn off the check engine light
* Smog check fraud being used in California
* Trouble codes - How to extract them and what the codes mean

OBDII Smog Machine Link - The State of California now requires all vehicles 1996 and up, to communicate directly with the smog machine during the smog test. This is achieved via your vehicle's OBDII Data Link Connecter.

As part of the smog inspection process, the smog technician will connect a Data Cable from the smog machine to your vehicle's OBDII Data Link Plug. This cable will deliver important "Check Engine" codes and "Readiness Flags" from the engine's computer system to the state's smog machine.

Emissions related failure codes will cause your vehicle to fail the smog inspection. The failure codes will be printed on the Vehicle Inspection Report (VIR) which will be given to you by the smog station.

Out-of-State Vehicles - It's true, there is a difference between California and Federal emissions equipped vehicles. And, for the most part California is much stricter when it comes to requiring vehicle manufacturers to equip their vehicles with smog reducing components.

However, a used federal vehicle which has all (or only) its federal required emission components, can pass the California smog inspection process and be legally registered in this state. In other words, California will not restrict consumers from purchasing and bringing into the state a used vehicle which is equipped with federal emissions components only, so long as the vehicle was designed that way by the manufacturer.

It will however not allow new federal vehicles into the state. New car dealers who wish to sell their products in California must import California emissions equipped vehicles only.

HE EMISSIONS TEST

First let's learn about smog. Smog is formed in our atmosphere when nitrogen dioxide and hydrocarbons (HC) react together in sunlight. The internal combustion engine produces, among other gases, nitrogen oxides (NOx), carbon monoxide (CO) and carbon dioxide (CO2). CO2 is not a problem, however when combined with nitrogen, it becomes a component of smog.

In an effort to reduce the formation of smog, we need to insure our engines' are emitting the least amount of hydrocarbons, carbon monoxides, and nitrous oxides into the atmosphere.

We must point out that the emissions test portion of the smog check process is where vehicles fail most. A properly maintained engine should not have any trouble passing the emissions test.

However, vehicles which are not, very often produce harmful emissions past the state's allowed limits, and subsequently fail this test. Simple timely engine maintenance will eliminate emissions failure causing problems.

The emissions test is only one part of the entire smog check process. Remember there the visual test and functional test sections of the smog inspection also. These two test will be administered after the emissions test.

THE EMISSIONS TEST: The first test the smog check center will administer as part of the entire smog inspection process is the emissions test. In order to pass the emissions test portion of the smog inspection your car's engine must be burning fuel efficiently, insuring hydrocarbons in it's combustion chambers are thoroughly spent.

Hydrocarbon put simply, is gasoline. The more gasoline your vehicle's engine combusts completely, the less pollutants are emitted into our air.

The emissions test will measure your vehicle's HC, CO and NOx production, and insure they are within the limits set by the State of California. Your vehicle's CO2 and O2 emissions are measured as well, however these results do not effect passing or failing the emission test.

Optimum fuel combustion is achieved when the engine can maintain a 14.7:1 air/fuel ratio during the combustion process with a constant variation +/- 5% to assist the catalytic converter operation.
14.7:1 air/fuel ratio insures your car is not burning or wasting fuel. If you notice your car is using up or burning too much gas, more then likely your vehicle's air to fuel ratio is rich.

Performing routine tune ups, which should include changing the spark plugs, air filter, fuel filter, and engine oil, either just before an emissions test, or as required by the vehicle's manufacturers will greatly improve your chances of passing the emissions test.

DYNAMOMETER USED: Counties in California with greater smog pollution require vehicle owners complete the Enhanced version of California's emissions test. The Enhanced smog test requires your vehicle to be driven on a dynamometer while the smog machine collects emission samples from the tailpipe. The Enhanced smog test has been proven to retrieve a more accurate sample of a vehicle's emissions output, then it's predecessor, the Basic smog test. The Basic smog test requires vehicles to be tested, only at idle and 2500 rpms. No dynamometer driving required.

If your county is in the Bureau of Automotive Repairs Enhanced list, no need to worry. There is nothing to do on your part. The smog stations in your area will be equipped to handle your vehicle's emissions test. Only thing you should consider is insuring proper tire inflation and avoid smog checking on rainy days.

FAILED THE EMISSIONS TEST
Help! My car failed the emissions test. What can I do? We get this question asked a lot. To answer it, first we'll have to find out which portion of the emissions test your vehicle is failing. Is your vehicle producing high HC, CO, or NOx? Failed Emissions Test

PASSING THE EMISSIONS TEST
How can my car pass the emissions test? This question comes in second. It is pertinent that your vehicle be regularly maintained in order to pass the emissions test.

THE VISUAL INSPECTION

During the visual portion of the smog inspection, the smog technician or mechanic will be looking for the presence and proper connection of several State of California required, emissions components. The visual portion of the smog test will include a Visible Smoke Test as well.

The smog technician must locate and verify that all emissions components are present and properly connected. Along with emissions components, the smog technician will also be looking for any defective or disconnected electrical connections, vacuum hoses and/or any pipe or plumbing which would effect engine performance and ultimately increase harmful smog emissions.

Note: During this part of the smog inspection process, the technician's inspection is only visual, and does not include testing emissions component for proper operation. The technician is required to simply locate the components visually, and insure they are properly connected. If a vehicle fails the smog inspection, it is up to the vehicle's owner to have individual emissions components inspected for damage or defects.
A. Emissions Components
During your personal inspection at home, ensure all hoses and wires are in place and properly connected. The following is a list of emission components that will be inspected by the smog technician:

* The Underhood Emission Label
* Exhaust Gas Recirculation Valve (EGR)
* Positive Crankcase Ventilation valve (PCV)
* Charcoal Canister (Evaporation Control System)
* Catalytic Converter (CAT)
* Oxygen Sensor (O2 Sensor)
* Air Injection System (AIR)
* Carburetor Pre-Heat Tube

Additional Emissions Components

The following emissions components are also part of the visual portion of the smog inspection. The smog technician will need to see that they are present and properly connected. Most modern vehicles are equipped with most of these components.

- Air Filter & Housing
- Throttle Position Sensor (TPS)
- Engine Coolant Temp Sensor (ECT)
- Manifold Absolute Pressure (MAP)
- Crankshaft Position Sensor (CKP)
- Camshaft Position Sensor (CPS)
- Intake Air Temperature Sensor (IAT)
B. Vehicle Smoke Test

Vehicles subject to a smog check require a visual inspection for excessive black or white smoke being emitted from the exhaust, and ultimately, the tailpipe.

This test is in addition to the tailpipe emissions test. The smog technician will be required to enter his/her observation into the smog machine after the emissions test portion of the smog check.

Excessive smoke, either black or white will cause a smog check failure. If your vehicle is emitting visible smoke, you will need to have the fault diagnosed and repaired before it can pass the smog check. Vehicles with severe engine damage may be emitting smoke from the engine compartment. This too will cause a visible smoke test failure.

What causes excessive black smoke? Visible black smoke may indicate one of two things.

1. The engine is not burning fuel properly, leaving behind high amounts of Carbon Monoxide (CO), resulting in excessive black smoke being emitted from the tailpipe. These vehicles will experience increased fuel consumption as well.

2. Engine oil is seeping into the combustion chambers. Oil is mixing with the fuel & air mixture, leaving behind high amounts of carbon, seen as excessive black smoke being emitted from the tailpipe. Oil seepage may occur due to defective piston rings, valve seals, or Positive Crank Ventilation (PCV) System.

What causes excessive white smoke: Visible white smoke may indicate a burned or blown head gasket. Excessive white smoke (steam) is caused by water seepage into the combustion chambers, which on a running engine, operate around 2500f. Water has an opportunity to enter the combustion chambers through the head gasket, at the junction of an engine's valve head and block. This will typically cause overheating and white smoke in the exhaust coming out of your car's tailpipe.

Note: Excessive white smoke should not be mistaken with normally emitted white smoke typically seen during cold days, and until an engine is properly warmed up. The smog check program is aware that vehicles may emit white smoke when cold, and insures a vehicle is properly warmed up prior to administering the smog test.

White smoke during startup or in cold weather is simply steam, and will not cause a smog check failure.

FUNCTIONAL INSPECTION

The final part of the entire smog test process is the functional inspection. The functional inspection is mainly conducted by the smog technician, and is hands-on. The smog technician will insure proper operation of the following emissions components and systems.

A. Engine Ignition Timing
B. Check Engine Light
C. Gas Cap & Filler Neck
D. Exhaust Recirculation Valve (EGR)
E. Fuel EVAP Test (LPFET)
A. Engine Ignition Timing
Your vehicle's engine ignition timing will be inspected during the smog test. The smog technician will insure ignition timing is set properly, and the system is supplying electric current to the sparkplugs at the correct intervals.

Spark, 15,000 to 20,000 volts, is created at the engine's ignition coil. Electricity is delivered to the coil, a spark is generated, then sent to the distributor. It is the distributors responsibility to route the spark to the correct spark plug, at the correct time. The timing inspection will insure the distributor is sending spark plug energy at the exact moment required for optimum air/fuel combustion. Adjusting a vehicle's ignition timing is performed by rotating the distributor clockwise or counterclockwise direction as needed.

Failed Ignition Timing: Engine ignition timing is measured in degrees. An ignition timing failure for example; ignition timing is required to be set at 15 degrees Before Top Dead Center (BTDC) and instead is set to 10 After Top Dead Center (ATDC). This fault will cause a functional failure, as well as increase Hydrocarbon (HC) emissions. California's emissions standards allow timing to be up to 3 degrees +/- off the manufacturer's required setting; resetting is recommend. One or two degrees off will not cause your vehicle to fail the ignition timing inspection.

Electronic Ignition Timing: Some late model vehicles may not have an ignition distributor, and therefore no timing adjustment or testing of the ignition system is required. On these engines, timing is controlled electronically by the Engine Control Unit, also known as the ECU, and the camshaft sensor and/or crankshaft sensor.

Both the crankshaft and camshaft sensors send vital data to the ECU indicating the position of the engine pistons, thus allowing the ECU to send spark to the proper cylinder at the exact moment fuel and air mixture is at it's optimum pressurization.

Any electronic ignition timing fault will automatically illuminate the check engine light, service engine soon light, or malfunction indictor lamp.

B. Check Engine Light (MIL)
My car's check engine light is on. Will I fail the smog test? Contrary to public belief, the check engine light, malfunction indicator lamp, or service engine soon light being constantly illuminated is an automatic smog failure. Vehicle manufacturers have placed the check engine light inside the passenger compartment to inform the driver that there has been an engine or drivetrain malfunction.

Often a vehicle's check engine light can be illuminated but the owner not notice any driveability concerns. Once the check engine light, malfunction indicator lamp (MIL), service engine soon lamp turns on, the engine's ECU (emissions control unit - may also be referred to as engine control unit or engine control computer) begins to operate under pre-programmed data rather then of real-time. In other words, the computer has sensed an error from an emissions component, and replaced the data from the component with data from it's memory.

How is the Check Engine Light tested? During the emissions inspection the check engine light is tested two ways. The first is conducted by the smog technician, and the second by the smog machine. The smog machine test only applies to vehicles 1996 model and newer. We will explain why later.

Part 1. OBD I & II "Check Engine Light" Test: During the smog technician's functional test, he/she will be looking for a constant or intermediate illuminated check engine light, malfunction indicator lamp, or service engine soon light. By the way... all three of these lights are similar in terms of being engine emissions trouble lights. Your vehicle is equipped with only one of these types of lights. Ford Motor Company will typically choose to use a service engine soon light instead of a check engine light. Honda chooses to use the check engine light. Each manufacturer has a preference. They all do the same thing.

The smog technician or mechanic will be looking for an illuminated check engine light during the smog inspection. Any time the check engine light is illuminated while the engine is running causes an automatic smog test failure. The only time the technician wants to see the check engine light on is when the ignition is in the ON position, and engine not running.

If the check engine light is not illuminated while the ignition is in ON position and engine off, this too causes an immediate smog check failure. The fact that the check engine light does not turn on during ignition ON may be due to a defective emissions control computer and/or a defective light bulb (Check Engine Light Lamp - 12v). Both are failures.

During the last phase of the smog test, the technician will be asked to enter your vehicle's check engine light visual results. He/She will enter the data as noted. Check engine light OFF or ON. That alone will determine your vehicle's success in passing the test or not.

Part 2. OBDII "Check Engine" Test: The second part of Check Engine Light test applies to 1996 or newer cars, trucks, SUVs, vans, and RVs only. These vehicles are equipped with an On Board Diagnostics (OBD II) system and input/output data link connecter (DLC). During the smog test your vehicle will be attached to the smog machine via it's OBD II DLC link connecter. The OBD II link will relay all "Check Engine" conditions along with stored trouble codes within it's database to the smog machine while the vehicle is being tested. If any trouble codes are present which caused the check engine light to illuminate either regularly or intermittently, the data will be sent to the smog machine via the data link connecter cable and the vehicle will fail the smog inspection.

The OBD II diagnostic system is designed to monitor all aspects of an engine's emissions control system, and report this information to a central database within the ECU (computer). This information is processed and checked against the computers pre-determined values for various inputs levels and performance patterns. If any problems are found, the computer will determine whether to alert the driver or not. If a decision has been made to alert the driver of an emissions problem, the "Check Engine" or "Engine Malfunction" light will illuminate on the vehicle's dashboard. In more serious emission conditions the computer may even begin to rapidly flash the "Check Engine/Malfunction" light indicating to the driver, that the vehicle needs immediate diagnosis/repair attention.

Part 3. OBDII "Readiness Flags" Test: Your 1996 and newer car, truck, van, SUV, or motorhome will not pass the smog test if certain "readiness flags" are not set. Some "check engine" related failures don't illuminate the check engine light, but do cause smog check failures. These faults are referred to as "readiness flag" faults. Readiness flags indicate that certain emissions systems which the OBD II computer has been monitoring have passed internal self monitoring tests, indicating that those systems are working properly. If the smog machine detects that there are certain readiness flags which have not set, the data will be relayed to the smog machine and your vehicle will fail the smog test.

In order to set all the proper Readiness Flags the OBDII system must complete at least one good drive cycle (in some cases two or three). A good drive cycle is a sequence of passing internal tests which the OBDII computer runs while your vehicle is being driven. This insures all emissions systems are functioning properly. A drive cycle usually requires one to two weeks of ordinary everyday driving.

Readiness flag failures are often seen on vehicles which have had recent repairs requiring disconnecting of the battery, and/or the emissions computer. Disconnection of power to the ECU resets all readiness flags. These vehicles will need to be driven in order to reset the required flags.

Part 4. OBDII "Trouble Code" Test: This OBDII test is not applicable to 1995 and older vehicles. Trouble codes indicate that the OBD II computer has detected a problem within the emissions system. The trouble code will specifically indicate the component and problem which was found. Newer vehicle's have very complex codes in the thousands. Smog check repair centers can retrieve the trouble codes from the OBDII and inspect the component/s which the codes indicate.

OBD-II Trouble Code Lookup - How to extract trouble codes using a trouble code scanner, and what do the codes mean?

What if I Fail the Check Engine Light Test? There are three ways your car may fail the check engine light test. You may fail in one or all three of the categories below.

Failure A. Check engine light, malfunction indicator lamp or service engine soon light illuminated, and smog technician enters this information into the smog machine.

- Repair for Failure A. Using a trouble code scanner, the smog technician must extract the trouble codes causing the check engine light to illuminate, and diagnose the responsible emissions components hands-on. Once problem/s are repaired, the vehicle must be driven to set proper readiness flags, and can then be retested.

Failure B. Smog machine detects an active OBD-II trouble code during the smog test via the OBD-II data link connecter. Check engine light is not currently illuminated, but may have been in the past.

- Repair for Failure B. After the smog test is complete the smog technician will hand over a Vehicle Inspection Report or VIR. The VIR will have printed at the bottom the trouble code/s which were extracted by the smog machine. The smog technician must use these code/s the conduct a hands-on diagnosis of the components in question. Usually a diagnose fee of two labor hours will be required. Average labor rate is $65.00 per hour.

Note: The trouble code/s will only direct the smog technician to the general area of the system failure. It is up to an emissions repair mechanic to inspect the system and emissions components for proper operation, and repair faults as necessary.

Failure C. Smog machine detects certain required "readiness flags" are not set. The reason for the flags not being set depends on the select readiness flag. Two possibilities apply for all readiness flag test failures:

* Recent disconnection of battery (12v) system. This is common on vehicles which have recently required removal or disconnections of the vehicle's battery or engine control computer.
* Vehicle has an emissions system failure not allowing "readiness flag" self tests to run.

- Repair for Failure C. If readiness flags are not set because your car's battery was recently disconnected, and your car's malfunction indicator lamp, check engine light, or service engine soon light is not illuminated, the repair might be simple.
Drive your vehicle for one week under normal driving conditions. During this period the emissions computer will run the proper readiness self tests to set the required "readiness flags". Your vehicle should not pass the smog check.

If this does not resolve the issue, or if the check engine light is illuminated, a more severe emissions failure may exist, requiring hands-on diagnosis by a smog check certified smog repair center.
How to erase trouble codes and turn off the check engine light

If you're performing this procedure to pass an emissions test when the check engine light, malfunction indicator lamp or service engine soon light is on or illuminated, read on and in detail to learn how the check engine light reset procedure works. The check engine light reset procedure applies to all vehicles.

You may have read information about how to turn off the check engine light or service engine soon light prior to the emissions test in order to pass the smog inspection, or emissions test. By turning off the check engine, malfunction indicator lamp or service engine soon light, in actuality deleting all emissions data from your vehicle's emissions computer, the smog machine will not know your vehicle has or has had emissions faults.

We will describe the reset or "turn off the light" procedure so you may understand the OBD (on board diagnostics) emissions testing process and how the check engine light or service engine soon light apply to the emissions test.

Warning! Perform this procedure at your own risk!

Step A. Locate your vehicle's battery. Disconnect the 12v positive cable (red wire) from battery terminal (+). Leave it disconnect for 10 minutes. While the battery is disconnected, cycle the ignition switch to ON position 3 times.

* Note you've just erased important emissions related data which is invaluable to a smog technician attempting to repair your vehicle.

* You also deleted very important "readiness flag" data which took many driving hours to compile.

Step B. Insure ignition switch is OFF. Reconnect the battery 12v positive cable (red wire) to battery terminal (+).

* You're risking electronic component damage. High voltage spark produced during the reconnection of the positive 12v cable can cause damage to fragile electronic emissions component/s.

Step C. Cycle ignition switch to ON position and wait 1 minute, then start your vehicle. Check Engine Light or Service Engine Soon Light should be reset and turned OFF.

* If you are successful in turning off the check engine light, this means your vehicle has not stored it's emissions data in the ROM section of it's computer and you have just deleted all data pertaining to your vehicle's engine and emissions systems, probably including your radio & system settings.

Step D. Drive your vehicle for one week under normal driving conditions. During this period the emissions computer is gathering data and re-learning your vehicle's emissions components and systems.
The emissions computer OBDII (on-board diagnostics) system must complete at least one drive cycle (in some cases two or three). A drive cycle is a sequence of internal tests which the emissions computer runs while your vehicle is being driven. This insures all emissions systems are functioning properly.

Proper "readiness flags" are set as the computer completes it's cycles. Test cycles are unique to a vehicle. Certain cycles run under very strict parameters, and may require extended driving time to trigger on. Cycle data and readiness flag information is available through your dealership's service department. The data vary widely.

* During your drive, maybe even as soon as you start the engine, your vehicle realizes an emissions fault, and turns on the Check Engine or Service Engine Soon light.

* Emissions computer refuses to set a required readiness flag. No check engine light, but no chance of passing the emissions test either. However, you will not know this until your vehicle is smog tested. If the particular emissions test center doesn't offer a free re-test, you forfeit your inspection fee.

Step E. Take the smog test. Important Note! Your vehicle might not be completely ready for the smog check inspection. Required parameters may have not been set by the emissions computer.

* Your vehicle might not be ready for the emissions test. There will be no way of knowing this until the smog test is complete. Your normal driving pattern (if not for an extended length of time) may have failed to trigger the emissions computer tests needed to set the required readiness flags.

Will I pass the smog check after erasing my car's trouble codes?

What are my chances of passing the emissions test after erasing the emissions computer data and turning off the check engine light?

A slight chance of passing the emissions test after a reset exists, but it is very slim. The trick is to get your vehicle smog checked before your engine computer detects the check engine light illuminating trouble code, and only after the required readiness flags have set. The chances of the engine computer setting the required readiness flags before detecting the trouble code and illuminating the check engine light are slim to none. In our opinion, time is better spent finding a reputable smog check repair station to diagnose the check engine or service engine soon light, then time spent trying to avoid detection and/or repairs.

Even after evading check engine trouble detection, passing the emissions test will require your vehicle's exhaust sample, which will be collected by the smog machine, fall within California Air Resource Board specifications, and all required emissions components be functioning properly. Remember passing the entire smog test requires your vehicle pass the visual, functional, and emissions portions of the test. One may be able to hide trouble code information by deleting data, but the vehicle's exhaust will not be able to hide high emissions.

Important Note: California law allows only a vehicle's registered owner or a State certified smog repair station conduct emissions related repairs. We recommend you insure the auto repair shop you visit is smog check certified. Smog check investigators will not get involved with faulty emissions repairs performed at non-emissions certified auto repair shops. Nor will they reimburse your costs if you end up applying for the CAP consumer assistance program.
C. Gas Cap & Filler Neck

During the smog test your vehicles gas cap and filler neck will also be inspected. They will have to be of proper fit and design. The gas cap must be able to hold pressure at factory specifications and the filler neck must not be altered to accept leaded gas. This test is to insure the vehicle is not polluting fuel tank fumes through the filler neck or using the wrong type of fuel. Most vehicles pass this portion of the smog test.

The test is conducted by the smog machine. You will notice the smog technician remove your car's gas cap and attach it to a gas cap receptacle on the smog machine. The smog machine will then pressurize the system and record if pressure is lost through the gas cap. A small amount of loss is allowed. If your vehicle's gas cap appears to be broken, does not fit properly, or has a broken or missing seal, it may fail the test.

What upsets consumers is that failing the gas cap test alone will cause the vehicle to fail the entire emissions test inspection. Even after all exhaust emissions pass successfully and no visual faults are found your vehicle will not pass the smog check.

The good side is the State of California will allow a vehicle owner to purchase a new gas cap from the smog station during the smog test. This allows the smog technician to continue the smog test, without having to fail the vehicle. The vehicle owner also has the choice of purchasing a new gas cap at a future date, however this would require the smog technician to fail the vehicle at the time of inspection. After a new cap is purchased a new smog inspection must be performed.

NOTE: A vehicle may fail the gas cap test, yet see no Check Engine light failure. The parameters required to pass the gas cap test and the parameters required to trigger the check engine light are not the same.

Loose Gas Cap Turning On the Check Engine Light - Late model vehicles have failed the emissions test due to a loose gas cap. Note however that a loose gas cap will trigger on the check engine light and you should not have your car inspected with the check engine light illuminated. The simple fault of not properly tightening the gas cap after filling up at a gas station has caused vehicles to fail the smog test.

This system works as such... the on board emissions computer runs a series of tests checking all major emissions systems and their components. The EVAP system is on the list. The computer runs a test on the EVAP system for vacuum. Note this is a very similar test to the LPFET test (which is discussed in section E of this page) which will be administered by the smog station, accept it is done by your vehicle's emissions computer. A loose gas cap will not allow the EVAP system to hold proper vacuum indicating either broken EVAP vacuum lines and/or disconnected connections, or a loose gas cap.
D. Exhaust Gas Recirculation Valve (EGR)

During the smog test your vehicle's EGR valve will be inspected for proper operation. This test applies to vehicles which are administered the "basic" California emissions test. your vehicle will not be driven on a dynamometer, and it's EGR valve will be manually checked.

How The EGR Valve is Tested - The EGR valve test process and what to do if your car fails or failed the EGR valve check.

EGR stands for exhaust gas recirculation. The EGR system recirculates exhaust gas back into the combustion chambers. Since these recycled exhaust gases have already been in the combustion chambers once, they have burned up most of their fuels, means there is now much less real fuel in the chambers to ignite. This keeps the chamber temperatures down and thus reduces NOx emissions. The EGR valve should be inspected to insure its proper operation. A working valve should be able to open its passage using manifold vacuum.

Manifold vacuum is created during the engine's intake cycle. The high demand for air during this cycle creates a vacuum within the engine's intake manifold. This vacuum is then used to control several important functions within the vehicle, including controlling the EGR valve. Some vehicles even rely on this vacuum to control their heating and air-conditioning components. The EGR system is prone to collecting carbon build-up. Some vehicle manufacturers recommend cleaning this component an a regular basis. Please Click on "Under Your Hood" for more information on EGR valves and testing procedures.

The following vehicles are equipped with EGR systems - Acura, Audi, Buick, Chevrolet, Chrysler, Dodge, Plymouth, Fiat, Ford, GM, GMC, Saturn, Honda, Hyundai, Infiniti, Isuzu, Jaguar, Jeep, Lexus, Mazda, Mercedes Benz, Mitsubishi, Nissan, Peugeot, Porsche, Renault, Land Range Rover, Saab, Saturn, Subaru, Suzuki, Toyota, Volkswagen, VW, Volvo, and Winnebago.
E. Low Fuel Pressure Evaporative Test (LPFET)

The low pressure fuel evaporative test is a test of your vehicle's EVAP system. The LPFET test is administered in addition to the entire smog inspection. 1976 to 1995 model year vehicles; car, truck, van, SUV, RV and motorhome will be tested, which includes all pre OBDII vehicles subject to a smog check.

How is the LPFET test conducted? The LPFET test is conducted by a BAR approved Low Pressure Fuel Evaporative Test machine. A pressure line is attached to your car's gas filler neck. Your vehicle's EVAP system and gas tank will be pressurized 0.5-1.0 psi (14”-28” column of water) and measured for 2 minutes. The allowable drop is .40 psi. A greater then .40 psi drop indicates a leaking EVAP system. The LPFET machine will display a failure. The data will be entered into the smog machine, causing your vehicle to fail the emissions inspection.

This test is designed to insure your vehicle's fuel evaporative system is not leaking gas fumes into the atmosphere. It is estimated that over 7,000,000 vehicles will need to be tested each year and of those 11% will fail. The average cost to repair a failed EVAP system is estimated to be approximately $250.00. The LPFET will result in a reduction of emission and will improve air quality.

What is a Smog Test Only Center?
What's a Test Only Center?
What is the difference?

What is the difference with a regular smog station and a test only station? You received your renewal notice and discovered it's asking for a smog inspection at a Smog Test Only Center. No need to panic.
All this means is that the DMV has chosen your car to be inspected at a special Test Only smog station. A Smog Test Only center, as the name suggests, can only smog test vehicles and is not allowed to perform automotive repairs. A test only smog check center has an obligation to insure a non-biased smog test inspection. They can not perform repairs.

The State of California uses the following three strategies to determine whether a vehicle is Test Only Center designated or not:

* Gross polluters (vehicles which have failed a previous smog inspection with very high emission readings)
* High Emitter Profile vehicles. These are vehicle types designated by the Bureau of Automotive Repair as having high chances of failing the smog inspection.
* A random sample of all vehicles registered in California and being driven on public roadways.

If your vehicle has been selected to undergo a Test Only smog check don't be alarmed. Simply locate a convenient smog test only center and proceed with the inspection.
The smog technician conducting the test can inform you of any serious issues. There are several Smog Test Only Centers throughout California and you can find one in your area using our CA Test Only Smog Station Locator.

Important Note: If your vehicle fails at a Test Only Smog Check center, you will need to seek repairs at a Test and Repair station. The Test and Repair smog station will need to conduct a new smog test - called a Baseline Test, and may charge you a smog inspection fee as part of their diagnosis and/or repairs.

Also note that a smog test only station is not allowed to perform or comment on any diagnosis or possible required repairs. Per California State law their primary obligation is to conduct a fair and unbiased smog test.

All and any repairs must be performed by a licensed smog check repair station, or the vehicle's owner personally.

How much does a test only smog check cost? Does a test only center charge more?
Smog test only stations are not allowed to profit or perform any auto repairs, whether smog check related or not. In the past smog test only centers typically charged more for their smog inspection in order to cover their expenses. In today's market however, with competition being so great, and the fact that there are plenty of test only directed vehicles to go around, the cost of the test only smog check has been dramatically reduced.

It is not uncommon to find smog centers performing the smog test for as low as $29.95 plus fees, which amount to approximately $40.00 out-the-door.