P0401

Tests 1 - 2:

Tests 3 - 7:

Tests 8 - 11:

Test 12:

SYMPTOM
P0401- EGR SYSTEM PERFORMANCE

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

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

POSSIBLE CAUSES
- Intermittent condition
- 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