With Generic Scan Tool

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

Recommended special tools and equipment







- VAG1526A hand multimeter
- VAG1594A connector test kit
- VAG1598/31 test box

Test requirements:
- Fuses for engine electronics OK
- Engine cold

Checking function
- Connect diagnostic tester. Diagnostic Tester, Connecting
- Switch ignition on.
- In diagnostic function "33 - OBD", select "Mode 1: Checking measured values".
- Select the desired measuring value "PID 05: Coolant temperature".
- Specified value: approx. ambient temperature


NOTE: If a temperature is indicated which differs greatly from ambient temperature of sensor, check sensor and sensor wires for contact resistances and open circuit.


- Start engine and let run at idle.
- Specified value: Temperature value must rise evenly


NOTE:
- The temperature increases in increments of 1.0 degree C.
- If the engine shows problems in certain temperature ranges and if the temperature does not climb uniformly, the temperature signal is intermittent and the sensor should be replaced.


- End diagnosis and switch ignition off.

If indications do not resemble description:

Checking internal resistance







- Disconnect electrical harness connector at Engine Coolant Temperature (ECT) Sensor -G2-/-G62- (arrow).







- Connect multimeter between terminal C and D of sensor for resistance measurement.

Range A displays resistance values for the temperature range of 0 ... 50 degrees C, range B displays resistance values for the temperature range of 50 ... 100 degrees C.







Read-out examples:
- 30 degrees C corresponds to a resistance of 1500 to 2000 Ohm
- 80 degrees C corresponds to a resistance of 275 to 375 Ohm

If specified value is not obtained:
- Replace Engine Coolant Temperature (ECT) Sensor -G62-, see -item 5-.

If specified value is obtained:

Checking wire connections
- Connect test box to wiring harness of Engine Control Module (ECM); ECM is not connected. Test Box, Connecting For Wiring Test







- Check the following wire connections for open circuit according to wiring diagram:

Harness connector Terminal Test box Socket
3 108
4 (signal) 93

- Specified value: Wire resistance max 1.5 Ohm

- Also check wires for short circuit to each other as well as to B+ and Ground (GND).
- Specified value: Infinite Ohm (no continuity)

- If necessary, repair wire connection.

If no malfunctions are found in wires:
- Replace Engine Control Module (ECM).

Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:
1 - Check DTC memory, see "Mode 3: Check DTC memory". Diagnostic Mode 3: Check DTC Memory
2 - If necessary, erase DTC memory, see "Mode 4: Reset/erase diagnostic data". Diagnostic Mode 4: Reset/Erase Diagnostic Data
3 - Generate readiness code. Readiness Code, Generating

- End diagnosis and switch ignition off.