Bulletin #04-07-30-013B addresses driveablilty issues in all GM cars and trucks. Some owners may install an aftermarket reusable air filter into their vehicle and then experience driveability issues, automatic transmission shift issues and/or an illuminated SES light.

The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF) sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from the MAF may be low and any or all of the following conditions may occur.

- Service Engine Soon (SES) light on



- Transmission shift conditions, slipping and damaged clutch(es) or band(s)



- Engine driveability conditions, poor acceleration from a stop, limited engine RPM range



To verify the condition, compare the MAF GPS reading with the reading of a like vehicle that has an OEM air box and filter under the same driving conditions.



If a vehicle is encountered with these conditions, check for a reusable aftermarket over-oiled air filter. If an aftermarket reusable air filter is used, inspect the MAF sensor element and the air induction hose for contamination of oil before making any warranty repairs.



DO NOT repair MAF sensors under warranty if concerns result from the use of an excessively/over-oiled aftermarket reusable air filter.



TIP: The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty.



TIP: Transmission or engine driveability concerns (related to the MAF sensor being contaminated with oil) that are the result of the use of an aftermarket reusable, over-oiled air filter are not considered to be warrantable repair items.



The other extreme is the UNDER-oiled air filter, which can also cause driveability concerns. The typical oiled aftermarket air filter requires cleaning and re-oiling at regular intervals to maintain optimum filtering.

Failure to do so eventually allows fine debris to pass through the filter. A buildup of debris on the MAF sensor reduces the sensor's ability to correctly detect airflow, leading to driveability concerns.