Diagnosis

Too much EGR flow at idle, cruise, or cold operation may cause any of the following conditions to occur:
^ The engine stalls after cold start
^ The engine stalls during closed throttle conditions
^ The vehicle surges during cruise
^ Rough idle
^ DTC P0300-Misfire detected

Too little or a lack of EGR flow may allow combustion temperatures to get too high. This could cause the following symptoms:
^ Spark knock or detonation
^ Engine overheating
^ Emission test failure
^ DTC P0401
^ Poor fuel economy

EGR flow diagnosis is included in the DTC P0401 diagnostic table. Pintle position error diagnosis is covered in DTC P1406. If EGR DTCs P0401 and/or P1406 are encountered, refer to Diagnostic Trouble Code (DTC) List for diagnosis.