Diagnostic Aids
WARNING: This page is about a different car, the 2003 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
Inspect for the following conditions:
- A vacuum restriction to the MAP sensor--A skewed MAP sensor reading 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 types of conditions can cause low engine vacuum and thus can cause a less than expected MAP changes 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 changes during the EGR flow test. Possible causes of this could be a restriction in the exhaust system or non Original Equipment Manufacture (OEM) exhaust parts.
- Exhaust system leaks can cause an insufficient amount of EGR flow through the EGR valve. This condition can cause a less than expected MAP changes due to insufficient exhaust back pressure. Possible causes of this could be a leaking exhaust system, a leaking EGR pipe or non Original Equipment Manufacture (OEM) exhaust parts.
- A restriction in the intake manifold such as carbon deposits and casting flash.
If condition is intermittent, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.