Exhaust Gas Recirculation: Testing and Inspection

PRE-TEST REQUIREMENTS
1. Engine coolant temperature at least 80°C (176°F).
2. All electrical consumers (including A/C) switched OFF.
3. Vacuum connections tight and without leaks.
4. Vacuum hoses not pinched or plugged.
5. Harness connector to the EGR temperature sensor connected.
6. Harness connector to the EGR Vacuum Regulator Solenoid Valve connected.
7. All vacuum lines are correctly connected.

TEST PROCEDURE
1. Ignition switch turned OFF.
2. Disconnect the temperature sensor harness connector.
3. Switch multimeter to 2 megohm scale.

Harness Connector Test Connection:

4. Using a test harness that allows the temperature sensor to remain connected while testing (VAG 1594 or equivalent) connect multimeter to the connectors as shown, use wires long enough to allow multimeter to be placed on the passenger seat.
5. START engine and let idle until it reaches operating temperature (radiator fan should cycle at least once).
6. Turn ignition switch OFF, wait ten minutes then check resistance.
^ Resistance should be at least 20,000 Ohms
^ IF NOT replace the EGR temperature sensor
7. RESTART engine and let idle for about three minutes.
8. Switch multimeter to 200k Ohm range.
9. Drive vehicle at a constant 50 - 60 MPH on a flat road for about two and a half miles.

NOTE: A/C should be OFF, driving should be done in HI gear.

10. During test drive resistance should reach.
^ At least 50,000 Ohms
11. If the resistance is less than 50,000 Ohms during entire test drive:
^ Check EGR system vacuum hoses and connections
^ Check EGR valve