Manufacturer's Scan Tool

Engine Coolant Temperature Sensor, Checking

Special tools, testers and auxiliary items required

• (VAG1526A)

• (VAG1594A)

• (VAG1598/31)

• (VAS5051) with (VAS5051/1)

Installation location. Refer to => [ Fuel Injection System Component Locations ] Locations

Test requirements

• Engine cold

Test sequence

- Connect testing and information system (VAS5051 ) and select vehicle system "01 - Engine electronics" in selection. Refer to => [ VAS 5051, Connecting and Select Functions ] VAS 5051, Connecting and Select Functions. Engine must be running at idling speed.

Display on (VAS5051):





- Under - 1 - select diagnostic function "08 - Read measured value block".

Display on (VAS5051):





1. Enter display group

- Enter "004" for "display group number 004" in zone - 2 - and confirm entry by pressing Q button.

Display on (VAS5051):





- Check indication in display field - 3 -.





If display zone 3 shows an implausible value:

- Disconnect connector - 2 - at Engine Coolant Temperature (ECT) sensor (G2)/ (G62).





- Connect multimeter between terminals C and D of sensor to measure resistance.





Range A shows resistance values for temperature range 0 to 50 °C and range B shows the values for temperature range 50 to 100 °C.

Sample readings:





• 30°C corresponds to a resistance of 1500 to 2000ohms

• 80°C corresponds to a resistance of 275 to 375 ohms

If specified value is not attained:

- Replace engine coolant temperature sensor.

If specified value is attained:

- Connect test box (VAG1598/31) to wiring harness for engine control module; do not connect engine control module. Refer to => [ Wiring and Component Check with Test Box VAG 1598/31 ] Wiring and Component Check With Test Box VAG 1598/31.

- Check for open circuit and short to positive or ground in following wiring connections:









- Test for short circuits between two wires.

- Repair any open/short circuit as necessary.

If no wiring malfunction is detected:

- Replace engine control module:

• With anti-theft housing. Refer to => [ Engine Control Module with Metal Anti-Theft Housing ] Engine Control Module With Metal Anti-Theft Housing.

• Without anti-theft housing. Refer to => [ Engine Control Module without Metal Anti-Theft Housing ] Engine Control Module Without Metal Anti-Theft Housing.