DN20 - Check For DTC 558

Diagnostic Trouble Code (DTC) 334 in Key On Engine Off (KOEO) or Engine Running (KOER) Self-Test indicates the EGR valve and/or EGR Valve Position (EVP) sensor may not be fully seated in the closed position. The EVP sensor voltage is greater than the closed limit voltage of 0.67 volt. Because of the preload on the installed EVP sensor, it is difficult to determine whether the EGR valve is seated or the EVP sensor is in contact with the EGR valve stem.

Possible causes:

- Poor continuity in EVP sensor harness.

- Non-seated EGR valve.

- Damaged EGR valve.

- Damaged EVP sensor.

- Damaged EGR Vacuum Regulator (EVR) solenoid.

- Damaged Powertrain Control Module (PCM).

- Key "OFF".

- Is DTC 558 present in KOEO Self-Test?

Yes -- Go to DN10. DN10 - Check Resistance of EVR Solenoid

No -- Go to DN21. DN21 - Rerun KOEO and KOER Self-Test W/EGR Vacuum Disconnected