Diagnostic Aids
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 Pontiac Grand Prix, 2003 Pontiac Bonneville, 2003 Chevrolet Monte Carlo, 2003 Chevrolet Impala, and 2003 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
Inspect for the following conditions:
- Vacuum restriction to MAP sensor. A skewed MAP sensor can cause the PCM to read incorrect MAP changes during the EGR flow test.
- An engine that is running poorly due to a mechanical condition such as worn piston rings, worn camshaft, etc. These type of conditions can cause low engine vacuum and thus can cause a less than expected MAP change during the flow test.
- Excessive back pressure in the exhaust system may cause this DTC to set. This condition can cause low engine vacuum and thus can cause a less than expected MAP change during the EGR flow test. Possible causes of this could be a restriction in the exhaust system or non-OEM exhaust parts.
- Exhaust system leaks cam cause an insufficient amount of EGR flow through the EGR valve. This condition can cause a less than expected MAP change due to insufficient exhaust back pressure. Possible causes of this could be a leaking exhaust system, a leaking EGR pipe or non-OEM exhaust parts.
- A restriction in the intake manifold such as carbon deposits and casting flash.