Circuit/System Testing
- Verify none of the following conditions exist:
- Incorrect EGR valve for engine application
- A vacuum leak between the EGR valve and the intake manifold
- Signs of external leakage usually indicated by carbon buildup around the mating surfaces of the components or an audible exhaust noise
- Restrictions in the passages or EGR valve caused by carbon deposits or casting flash
- Leaks or restrictions at the MAP sensor
- Leaking, restricted, or modified exhaust system-Refer to Symptoms - Engine Exhaust .
- Mechanical failure in the engine such as worn piston rings, camshaft or incorrect timing belt installation-Refer to Symptoms - Engine Mechanical .
IMPORTANT: Restrictions can cause excessive back pressure and low engine vacuum. - Ignition OFF, disconnect the harness connector of the EGR valve.
- Ignition OFF, verify a test lamp does not illuminate between the control circuit and B+.
- If test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.
- If all circuits test normal, test or replace the EGR valve.