Diagnostic Aids

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.