Exhaust Gas Recirculation: Testing and Inspection

EGR Valve Flow:

Too much EGR flow at idle, cruise, or cold operation may cause any of the following conditions to occur:

^ Engine stalls after cold start.
^ Engine stalls during closed throttle conditions.
^ Vehicle surges during cruise.
^ Rough idle.
^ DTC P0300 (misfire detected).

Too little or no EGR flow may allow combustion temperatures to get too high. This could cause the following symptoms:

^ Spark knock (detonation).
^ Engine overheating.
^ Emission test failure.
^ 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 diagnostic trouble code P1406 is encountered, go to the DTC tables for diagnosis.