Code P0401, EGR Flow Test Failure: Notes
Control module tests exhaust gas recirculation valve by momentarily commanding valve on while monitoring engine RPM. Control module will illuminate Malfunction Indicator Light (MIL) and store Code P0401 if expected drop is not seen for a calibrated number of tests.
NOTE:
Test numbers refer to numbers on diagnostic chart.
- Ensures EGR valve is allowing EGR flow and control module is capable of controlling EGR valve.
- Ensures control circuit is not shorted to ground.
- Ensures control circuit is not open and that control module quad-driver for circuit is properly functioning.