Cause can also be from stupid so called performance mods such as from Halltech that opens the bottom edge and installs some "rammer" that really causes air turbulance or so called "free" mods that have you wedge open the bottom of shroud.

08-06-04-040: Malfunction Indicator Lamp (MIL) - Check Engine Light On, DTCs P0171 and/or P0174 Set (Perform Repair As Outlined) - (Aug 13, 2008)

Models: 2007-2009 Chevrolet Corvette (Including Z06)

Condition

Some customers may comment that the check engine light is on.

A scan tool may reveal DTCs P0171 and/or P0174 set in history or current. If the air flow to the air intake/air cleaner assembly is disturbed, the DTCs may be induced.

Cause

This condition may be caused by a gap between the upper radiator air baffle and the bumper beam combined with some beam holes.
The gap and holes may cause an air flow disturbance to the air intake/air cleaner assembly. Refer to the pictures below for further clarification.

Correction

Look at the upper radiator air baffle with a large gap that needs to be repaired.
Repair the gap in the panel by making sure the retaining clips are properly seated or by installing new retaining clips, P/N 05973400.
To access these clips, the vehicle needs to be raised and the three bolts securing the lower radiator air baffle to the bumper beam need to be removed.

Look at upper radiator air baffle with a good fit but the bumper beam holes need to be covered with a good adhesive type patch (sound deadener patch) or equivalent.

Sound deadener patches can be obtained from Kent Automotive*. to obtain Kent P/N P20617.

Remove the air cleaner assembly for access. Clean the bumper beam as necessary and install the patch so the holes are covered. No air can flow through these holes.

Evaluate the lean condition after the upper radiator air baffle gap has been repaired and the bumper beam holes have been covered.

Note:

Any modifications to the air intake/air cleaner assembly must be removed before attempting repairs for the lean condition.

*We believe this source and their products to be reliable. There may be additional manufacturers of such products.

General Motors does not endorse, indicate any preference for or assume any responsibility for the products from these firms or for any such items which may be available from other sources.