HE31 - Check DPFE SIG Voltage While Exercising EGR Valve

- Key On, Engine Off.

- View DPFE PID with a Scan Tool and make note of voltage.

NOTE: Typical DPFE SIG voltage with no EGR flow is 0.45 volts +/- 0.25 volts.

- Disconnect vacuum hose at EGR valve and plug hose.

- Connect a hand vacuum pump to EGR valve.

- Start engine and bring to idle.

- Observe DPFE PID at idle and compare to the key on Engine Off voltage. (A higher voltage at idle could be due to a non-seating EGR valve.)

- Apply just enough vacuum to EGR valve to open it (2 to 3 inHg) without stalling engine and release vacuum. Repeat several times while observing DPFE PID on Scan Tool. (DPFE PID voltage should increase as valve begins to open and return to initial value as vacuum is released. A slow to return voltage could be an indication of a binding or a slow closing EGR valve.)

- Does the DPFE PID voltage indicate an open, binding or slow closing EGR valve?

YES -- REMOVE and INSPECT the EGR valve for signs of contamination, 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

NO -- RECONNECT EGR vacuum hose. GO to HE32. HE32 - Monitor EGR Valve Vacuum While Wiggling EVR Circuit