P0401

Test 1 - 2:

Test 3 - 7:

Test 8 - 11:

SYMPTOM
P0401- EGR SYSTEM PERFORMANCE

WHEN MONITORED
During engine decel, 26 to 4 MPH. Engine Coolant Temp greater than 70° C (158° F). Engine run time greater than 120 seconds.

SET CONDITION
The PCM monitors engine roughness. During decel, the EGR is opened and the PCM monitors engine then monitors engine roughness with the valve open. If an increase of engine roughness is not present, an error is detected. Two Trip Fault.

POSSIBLE CAUSES
- Good trip equal to zero
- EGR valve open at idle
- EGR valve assembly inspection
- EGR solenoid assembly
- EGR solenoid ground circuit open
- EGR solenoid control CKT short to GND
- EGR solenoid control CKT shorted to voltage
- EGR solenoid control CKT open
- PCM - EGR open
- PCM - EGR closed