Diagnostic Aids

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