System Diagnosis - EGR

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

^ The engine stalls after a cold start.
^ The engine stalls 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. P0401

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 overheat DTC.
^ DTC P0401.

System Check
The following table covers the diagnosis of the EGR system:

^ Linear EGR System Check. System Check - EGR