Exhaust Gas Recirculation: Testing and Inspection

Results Of Incorrect Operation
With too much EGR flow at idle, cruise, or cold operation, any of the following conditions may occur:

^ The engine stops after a cold start.
^ The engine stops at idle after deceleration.
^ The vehicle surges during cruise.
^ The vehicle idles roughly..

If the EGR valve stays open all of the time, the engine may not idle. A DTC P0401 may set. Refer to DTC P0401 EGR System Flow Insufficient. Testing and Inspection

Too little or no EGR flow allows the combustion temperatures to get too high during acceleration and load conditions. This could cause the following conditions:
^ Spark knock (detonation)
^ Engine overheating
^ DTC P0401

System Check
The Linear EGR System Check table covers the diagnosis of the EGR system. Refer to EGR System Diagnosis. Testing and Inspection

Diagnostic Trouble Code (DTC) P0401 or P1406 indicates that there is a failure in the EGR system circuit. Refer to DTC P0401 EGR System Flow Insufficient or DTC P1406 EGR Valve Pintle Position Circuit. Refer to System Diagnosis / Diagnostic Tables for testing information. Testing and Inspection