P0401

Tests 1 - 2:

Tests 3 - 7:

Tests 8 - 11:

Test 12:

SYMPTOM
P0401- EGR SYSTEM FAILURE (4 CYLINDER)

WHEN MONITORED
With the ignition ON and the battery voltage greater than 10.4 volts.

SET CONDITION
Conditions are met, the EGR is turned OFF and ON momentarily. The oxygen sensor signal is monitor for changes in its output signal during this test. If no significant change or too much change is seen, a flag is set.

POSSIBLE CAUSES
- Intermittent Condition
- EGR Solenoid Vacuum Supply
- EGR Valve Operation (Closed)
- ASD Output Circuit Open
- EGR Valve Operation (Open)
- EGR Solenoid Control Circuit Shorted To Voltage
- EGR Solenoid Control Circuit Open
- EGR Solenoid (Closed)
- EGR Solenoid Control Circuit Short To GND
- EGR Solenoid (Open)
- PCM
- PCM (Closed)