Test Description

NOTE: Test numbers refer to numbers on diagnostic chart.

Ensures EGR valve is allowing EGR flow and PCM is capable of controlling EGR valve.
Ensures control circuit is not shorted to ground.
Ensures control circuit is not open and that PCM quad-driver for circuit is properly functioning.

Fig 1: Code P0401 Schematic (3.8L) (EGR) Flow Test Failure

Fig 2: Code P0401 Diagnostic Flow Chart (3.8L) (EGR) Flow Test Failure