HE91 - Check EGR Valve Operation

- Key Off.

- Disconnect vacuum hose at EGR valve and connect a hand vacuum pump to EGR valve.

- View DPFE PID with a Scan Tool.

- Key On, engine running.

- Slowly apply 5 to 10 inHg of vacuum to the EGR valve, hold vacuum for 5 seconds and release. (Increase rpm slightly if engine begins to stall.)
- Look for a smooth operation of the EGR valve without binding. The DPFE PID voltage should increase once the EGR valve begins to open and until its fully open.
- While holding vacuum to EGR valve, look for a vacuum leakage causing the valve to close.

- Does the EGR valve open smoothly and hold vacuum?

YES -- GO to HE92. HE92 - Inspect EGR Vacuum Signal For Intermittent Failure

NO -- REMOVE and INSPECT EGR valve for signs of damage, leakage, contamination, icing, unusual wear, carbon deposits, binding and other damage. SERVICE as necessary (use Rotunda EGR Valve Cleaner 021-00056, if needed). RECONNECT all components. Complete PCM reset to clear DTCs. Clearing Diagnostic Trouble Codes

Rerun quick test. Diagnostic Subroutines (DSR) - Extracting Codes