DL34 - Check Signal at the PFE/DPFE Inlet Hose(s)

- Key "OFF".

- Disconnect and inspect the Pressure Feedback EGR (PFE) / Differential Pressure Feedback EGR (DPFE) inlet hose(s) for kinks, blockages, etc. Service as necessary and reconnect after inspection.

- Tee in a standard vacuum gauge at the PFE/DPFE inlet hose (downstream signal).

- Rerun Key On Engine Running (KOER) Self-Test. Key ON Engine Running (KOER) Self-Test

- Is there a momentary increase in vacuum gauge reading during KOER Self-Test (indicating EGR valve is opening)?

Yes -- Remove vacuum gauge. Rerun quick test if the inlet hose(s) needed service. Quick Test Appendix (Detailed Testing Instructions)

If service was not needed, then Go to DL35. DL35 - Attempt to Generate KOEO Code 337

No -- Remove and Inspect the EGR valve for signs of contamination, unusual wear, carbon deposits, grinding, and other damage. Service as necessary (use Rotunda 021-80056 EGR valve cleaner if needed). Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)