With Manufacturer's Scan Tool

Engine Coolant Temperature (ECT) Sensor -G62-, Checking

Special tools and equipment
- VAG 1551 Scan Tool or VAG 1552 with cable
- VAG 1551/3
- Test box VAG 1598/22
- Hand multimeter VAG 1526 or multimeter VAG 1715
- Adapter set VAG 1594
- Wiring diagram

NOTE: The engine control module will use the intake air temperature as a replacement value for an engine start (start temperature replacement value) as soon as there is a malfunction stored in the DTC memory, which affects the engine coolant temperature (ECT) sensor -G62-. The temperature then rises according to a model stored in the control module. When the engine has reached normal working temperature a fixed replacement value will be displayed after a certain period. This fixed value is also dependent upon the intake air temperature.

Test conditions
- Engine must be cold.

Test sequence
- Connect VAG 1551 Scan Tool ((VAG 1552). Then switch ignition on and select engine control module with "Address word" 01.(Connecting scan tool and selecting engine control module).

Indicated on display

Rapid data transfer HELP
Select function XX

- Press keys 0 and 8 for function "Read Measuring Value Block" and confirm entry with Q key.

Indicated on display

Read Measuring Value Block HELP
Input display group number XX

- Press keys 0, 0 and 4 for "Display group number 4" and confirm entry with Q key.

Indicated on display: (1 to 4 Display zones)

Read Measuring Value Block 4 ->
1 2 3 4

If the specification is not obtained:
- Read off coolant temperature value in display zone 3.
Specification: approx. coolant temperature
- Perform check according to following table:

Display1) Cause
Approx. -46 degree C Open circuit or short to positive
Approx. 141 degree C Short to Ground
1) If a temperature is displayed which deviates greatly from the ambient temperature of the sensor, check sensor wiring for transfer resistances.

If the specification is obtained:
- Start engine and run at idle speed. Temperature value must increase uniformly.

NOTE:
- Temperature rises in steps of 1.5 degree C.
- If irregular engine running occurs in certain temperature ranges and the temperature figure does not increase without interruption, the temperature signal is temporarily interrupted and the sensor must be replaced.

- Press -> key.
- Press keys 0 and 6 for function "End Output" and confirm entry with Q key.

Continuation of check when display approx. -46 degree C:







- Pull 4 pin connector -1- off coolant temperature sensor -G62- -2-.
- Bridge connector contacts 1+3 using auxiliary cables from VAG 1594 and observe display.

If display jumps to approx. 141 degrees C:
- Press -> key.
- Press keys 0 and 6 for "End data transfer" function and confirm input with Q key.
- Switch ignition off.
- Replace engine coolant temperature (ECT) sensor -G62-.

If display jumps to approx. -46 degree C:
- Press -> key.
- Press keys 0 and 6 for "End data transfer" function and confirm input with Q key.
- Switch ignition off.
- Check wiring using wiring diagram.

Continuation of check when display approx. 141 degree C:







- Pull 4 pin connector -1- off engine coolant temperature (ECT) sensor -G62- -2-.

If display jumps to approx. -46 degree C:
- Press -> key.
- Press keys 0 and 6 for "End data transfer" function and confirm input with Q key.
- Switch ignition off.
- Replace engine coolant temperature (ECT) sensor -G62-.

If display remains at approx. 141 degree C:
- Press -> key.
- Press keys 0 and 6 for "End data transfer" function and confirm input with Q key.
- Switch ignition off.
- Check wiring using wiring diagram

Checking wiring







- Connect test box VAG 1598/22 to control module wiring harness.







- Check wires between test box and 4-pin connector for open circuit according to wiring diagram.
Contact 4 + vehicle ground
Contact 3 + socket 53
Wire resistance: max. 1.5 Ohm
- Check wires for short circuit to each other as well as to vehicle Ground.
- Check both wires for short to battery positive.

If no malfunction in wire is detected:







- Perform resistance measurement on engine coolant temperature (ECT) sensor -G62- contact C (signal) and D (Ground).







- Scale A shows resistance values for temperature range 0 to 50 degree C and scale B the values for temperature range 50 to 100 degree C.

Examples:
- 30 degree C is in range A and corresponds to a resistance of 1.5 to 2.0 kOhm
- 80 degree C is in range B and corresponds to a resistance of 275 to 375 Ohm

If the specification is not obtained:
- Replace engine coolant temperature (ECT) sensor -G62-.

If there is no malfunction in the wiring and the resistance measurement values are OK.:
- Replace engine control module.