DN25 - Check EVP Sensor and EGR Valve Operation

DTC 328 in Key On Engine Off (KOEO) and Key On Engine Running (KOER) indicates the EGR valve and/or EGR Valve Position (EVP) sensor voltage is lower than normal in the closed position. The EVP voltage is less than the closed limit voltage of 0.24 volts. Because of the preload of the EVP sensor, it is difficult to determine whether the EGR valve has malfunctioned or the EVP sensor has an abnormally high resistance.

Possible causes:

- Poor continuity in EVP sensor harness or connectors.

- Damaged EGR valve.

- Damaged EVP sensor.

- Damaged Powertrain Control Module (PCM).

- Key "OFF".

- Disconnect EVP sensor.

- Inspect the connectors at harness and sensor for damaged pins, corrosion, loose wires, etc. Service as necessary.

- Remove vacuum line from EGR valve.

- Exercise EGR valve by applying and releasing vacuum with a vacuum pump.

- Reconnect vacuum line to EGR valve and electrical connector to EVP sensor.

- Rerun KOEO and KOER Self-Test. Quick Test Appendix (Detailed Testing Instructions)

- Is DTC 328 still present?

Yes -- Go to DN26. DN26 - Check EVP Signal Voltage

No -- The original DTC 328 was the result of poor continuity at the EVP sensor connector or binding of the EGR valve stem by contaminants. Testing complete.