DN22 - Check EVP Sensor and EGR Valve Operation

- Key "OFF".

- Disconnect EGR Valve Position (EVP) sensor.

- Inspect the connectors on 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 Key On Engine Off (KOEO) and Key On Engine Running (KOER) Self-Test. Quick Test Appendix (Detailed Testing Instructions)

- Is Diagnostic Trouble Code (DTC) 334 still present?

Yes -- Go to DN23. DN23 - Check EVP Signal Voltage

No -- The original DTC 334 was the result of poor continuity at the EVP sensor connector or binding of the EGR valve stem by contaminants. Testing complete.