EGR Valve: Testing and Inspection

Fig. 7 Connecting Vacuum Hose to EGR Valve:

Requirements:
Engine coolant temp. at least 80°C (176°F).
All electrical consumers (including A/C) switched OFF.
Radiator fan must not be running while performing tests.
Vacuum connections must all be tight and without leaks.
Vacuum hoses must not be pinched or plugged.

1. Disconnect vacuum hose from the EGR valve, Fig. 7.
2. Connect a hand vacuum pump to the vacuum port on the EGR valve.
NOTE, do not run the engine while performing this test.
3. Using the hand vacuum pump, apply 600 mbar (17.7 in Hg) vacuum to the EGR valve. Vacuum should not drop to less than 500 mbar (15 in Hg).
If vacuum drops below specification, or will not build up to the test value, check the hose connections for leaks and make sure the vacuum pump is operating correctly.
If the pump and lines are OK, replace the EGR valve.
4. Disconnect the EGR temperature sensor harness plug.
5. Switch multimeter to resistance range.
6. Connect the multimeter between terminals 1 and 2 of the EGR temperature sensor.
7. Start the engine and run at about 2000 RPM.
8. Using the vacuum pump, apply a vacuum of 130 +/- 20 mbar (3.8 +/- 0.6 in Hg) to the EGR valve. Resistance should be between 1000 and 19,000 ohms.
If the resistance is not within specification, replace the EGR valve.
If the resistance is OK, and the valve does not function correctly, replace the EGR frequency valve.