Without VAG 1551

PRE-TEST REQUIREMENTS
^ Engine coolant temperature at least 80°C (176°F).
^ All electrical consumers (including A/C) switched OFF.
^ Radiator fan must not run while performing tests.
^ Vacuum connections tight and without leaks.
^ Vacuum hoses not pinched or plugged.

TEST PROCEDURE
- Disconnect vacuum hose from EGR valve.

EGR Temperature Sensor Checking:

- Connect a hand vacuum pump to EGR valve.

NOTE DO NOT run engine during this test.

- Using hand vacuum pump, apply vacuum to EGR valve.

^ Vacuum should hold without dropping.

- If vacuum drops, or will not build up:

^ Check hose connections for leaks.
^ Check vacuum pump operation.

- If pump and lines are OK, replace EGR valve.
- Disconnect EGR temperature sensor harness connector.
- Switch multimeter to resistance range.

Connector 2-wire:

- Connect multimeter between terminals 1 and 2 of EGR temperature sensor.
- START engine and run at approx. 2000 RPM.
- Using vacuum pump, apply vacuum to the EGR valve, then check resistance:

^ Resistance should be 1000 to 19,000 ohms.
^ IF NOT replace the EGR valve.