Coolant Temperature Sensor/Switch (For Computer): Testing and Inspection

Signal From Coolant Temperature Sensor, Checking

Special Tools and Equipment







- VAG1526A
- VAG1594A
- VAG1598A
- VAG1598/25
- VAS5051 with VAG5051/1

Test requirement:
- VAS5O51 tester connected

Test sequence

If a malfunction of the Engine Coolant Temperature (ECT) gauge is detected at the instrument cluster, check if the signal at the instrument cluster is OK.
- Read measuring value block display group 003.







- Check indication in display field -1-.

If the coolant temperature is indicated, instrument cluster is malfunctioning.
- Replace instrument cluster.

If the Engine Coolant Temperature (ECT) is not indicated:
- Check signal at multi-pin harness connector at instrument cluster.
- Remove instrument cluster.
- Connect VAG1598A test box to blue 32-pin multi-pin harness connector using VAG1598/25 adapter.
- Connect multimeter between terminal 8 and 7 (sensor Ground (GND)) for resistance measurement.

Engine coolant temperature in °C Resistance in ohm
90 approx. 110
120 approx. 50

If specified values are not obtained:
- Check wire connection between instrument cluster and Engine Coolant Temperature (ECT) sensor according to wiring diagram.

If no malfunctions are found in wire:
- Replace coolant temperature sensor.