EGR Valve Check

Comp. Loc:

WARNING: If the EGR valve is hot, it may be necessary to wear gloves to avoid burning fingers.

1. Start and run engine to normal operating temperatures.
2. Raise and suitably support vehicle drive axles.
3. Place the transmission in neutral and the transfer in "2H." Check that the propeller shaft is turning (ECM must see VSS input for operation of EGR solenoid vacuum valve).
4. Place finger on Exhaust Gas Recirculation (EGR) valve diaphragm and accelerate engine; diaphragm should move.
5. Disconnect vacuum hose from EGR valve.
6. Using a vacuum pump, apply 27 kPa (8 in Hg) of vacuum to EGR valve with finger on diaphragm. The diaphragm should move and engine should run rough and may stall.

^ Check for carbon in valve which may cause restriction. Restriction may be small enough so that the engine may not stall during Step 4, but large enough to cause a DTC to set. It valve fails, replace the valve. If the valve passes the above test, check the Exhaust Gas Recirculation (EGR) pressure transducer. Refer to EGR Backpressure Transducer / Testing and Inspection. Testing and Inspection