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With Manufacturer's Scan Tool



Engine Coolant Temperature (ECT) Sensor, Checking

NOTE: The Engine Control Module (ECM) will use a replacement temperature value for an engine start as soon as there is a DTC 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 ECM. 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 on intake air temperature.

Special tools, test equipment and auxiliary items
- Scan tool V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3B
- Test box V.A.G 1598/31
- Hand multimeter V.A.G 1526 or multimeter VAG 1715
- Adapter set V.A.G 1594
- Wiring diagram

Test conditions
- Engine must be cold

Test sequence

NOTE: Only gold-plated contacts must be used to repair the contacts 1 and 3 in the connector for the Engine Coolant Temperature (ECT) sensor.

- Connect the scan tool V.A.G 1551 (V.A.G 1552). Then switch ignition on and select engine control module with the "Address word" 01. Connecting scan tool and selecting Engine Control Module (ECM). [1][2][3]Connecting VAG 1551 Scan Tool

Indicated on display

Rapid data transfer HELP
Select function XX

- Press keys 0 and 8 for the function "Read measuring value block" and confirm entry with Q key.

Indicated on display

Read measuring value block
Input display group number XXX

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

Indicated on display (1-4 = Display zones)

Read measuring value block 4 ->
1 2 3 4

- Read off coolant temperature value in display zone 3.

Display Group 4:






- Start engine and run at idle speed. The temperature value must increase uniformly

If the specification is not obtained:
- Press -> key.
- Press keys 0 and 6 for the "End output" function and confirm input with the Q key.
- Switch off ignition.
- Replace Engine Coolant Temperature (ECT) sensor (G62) with coolant temperature gauge sender (G2), item 26.

NOTE: The temperature rises in steps of 1.0 °C.

- Check DTC memory, if necessary, repair any malfunctions and then erase DTC memory, checking and erasing DTC memory. Reading Diagnostic Trouble Codes

- Read-out the readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
If the DTC memory has been erased or the engine control module was disconnected from permanent positive, the readiness code must be generated again. Monitors, Trips, Drive Cycles and Readiness Codes

Evaluating display group 4, display zone 3 - Coolant temperature

Display Zone 3:






Continuation of check when display approx. -45 °C:





- Pull the 4 pin connector off Engine Coolant Temperature (ECT) sensor (G62) with coolant temperature gauge sender (G2) - arrow-.






- Bridge connector contacts 1 + 3 using aux. cables from V.A.G 1594 and observe display.

If display jumps to approx. 143.0 °C:
- Press key.
- Press keys 0 and 6 for the "End output" function and confirm input with the Q key.
- Switch off ignition.
- Replace Engine Coolant Temperature (ECT) sensor (G62) / coolant temperature gauge sender (G2), item 26.
- Check DTC memory, if necessary, repair any malfunctions and then erase DTC memory, checking and erasing DTC memory. Reading Diagnostic Trouble Codes
- Read-out the readiness code. If the DTC memory has been erased or the engine control module was disconnected from permanent positive, the readiness code must be generated again. Monitors, Trips, Drive Cycles and Readiness Codes Monitors, Trips, Drive Cycles and Readiness Codes

If display remains at approx. -45.0 °C:
- Press -> key.
- Press keys 0 and 6 for the "End output" function and confirm input with the Q key.
- Switch off ignition.
- Check wiring using wiring diagram.

Continuation of check when display approx. 143.0 °C:





- Pull the 4 pin connector oft Engine Coolant Temperature (ECT) sensor (G62) with coolant temperature gauge sender (G2) - arrow-.

If display jumps to approx. -45.0 °C:
- Press -> key.
- Press keys 0 and 6 for the "End output" function and confirm input with the Q key.
- Switch off ignition.
- Replace Engine Coolant Temperature (ECT) sensor (G62) / coolant temperature gauge sender (G2), item 26.
- Check DTC memory, if necessary, repair any malfunctions and then erase DTC memory, checking and erasing DTC memory. Reading Diagnostic Trouble Codes
- Read-out the readiness code. If the DTC memory has been erased or the engine control module was disconnected from permanent positive, the readiness code must be generated again. Monitors, Trips, Drive Cycles and Readiness Codes Monitors, Trips, Drive Cycles and Readiness Codes

If display remains at approx. 143.0 °C:
- Press -> key.
- Press keys 0 and 6 for the "End output" function and confirm input with the Q key.
- Switch off ignition.
- Check wiring using wiring diagram.

Checking wiring
- Remove inner plenum chamber cover, left:






- Connect test box V.A.G 1598/31 to control module wiring harness. The engine control module is not connected by this action.






- Pull the 4 pin connector off Engine Coolant Temperature (ECT) sensor (G62) with coolant temperature gauge sender (G2) - arrow-.






- Check wire for open circuit between test box and 4-pin connector using wiring diagram.
- Contact 1 + Socket 108
- Contact 3 + Socket 93
Wire resistance: max. 1.5 Ohms

- Check wire for short circuit between test box and 4-pin connector contact 1 to wire contact 3 and to vehicle Ground using wiring diagram.
- Contact 3 + socket 108
- Contact 3 + vehicle Ground
Specification: Infinity Ohms

- Additionally check both wires for short to battery positive.
Specification: Infinity Ohms

If no wiring malfunctions are detected:






- Perform resistance measurement on Engine Coolant Temperature (ECT) sensor (G62) contact 1 (Ground) and 3 (signal).






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

Examples:
- 30 °C corresponds to a resistance from 1500-2000 Ohms
- 80 °C corresponds to a resistance from 275-375 Ohms

If the specification is not obtained:
- Replace Engine Coolant Temperature (ECT) sensor (G62) / coolant temperature gauge sender (G2), item 26.
- Check DTC memory, if necessary, repair any malfunctions and then erase DTC memory, checking and erasing DTC memory. Reading Diagnostic Trouble Codes
- Read-out the readiness code. If the DTC memory has been erased or the engine control module was disconnected from permanent positive, the readiness code must be generated again. Monitors, Trips, Drive Cycles and Readiness Codes Monitors, Trips, Drive Cycles and Readiness Codes

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