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With Manufacturer's Scan Tool




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

NOTE: The Motronic Engine Control Module (ECM) -J220- 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
- VAG 1551 scan tool or VAG 1552 mobile scan tool with VAG 1551/3B cable
- VAG 1598/31 test box
- VAG 1526 hand multimeter or VAG 1715 multimeter
- VAG 1594 adapter set
- Electrical Wiring Diagram

Test conditions
- Engine must be cold

Test sequence

NOTE: Only gold-plated terminals must be used to repair the terminals 3 and 4 in the connector for the Engine Coolant Temperature (ECT) sensor.

- Connect VAG 1551 scan tool (VAG 1552). Switch ignition on and select Motronic Engine Control Module with "Address word" 01.

Indicated on display

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -8- for function "Read measuring value block" and confirm entry with -Q- button.

Indicated on display

Read measuring value block
Input display group number XXX

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

Indicated on display (1 to 4 = Display zones)

Read measuring value block 4 ->
1 2 3 4

- Read Engine Coolant Temperature (ECT) value in display zone 3.
Specification: approx. Engine Coolant Temperature (ECT)






If the specification is not obtained:
- Perform check according to following table:

Evaluating display group 4, display zone 3 - Engine Coolant Temperature (ECT)






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

NOTE:
- Temperature increases in steps of 1.0 °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 -> button.
- Press buttons -0- and -6- for "End output" function and confirm input with -Q- button.

Continuation of check when display approx. -48 °C:






- Disconnect 4-pin connector from Engine Coolant Temperature (ECT) sensor -G62- with Engine Coolant Temperature (ECT) sensor -G2- -arrow-.






- Bridge connector terminals 3 + 4 using auxiliary cables from VAG 1594 and observe display.

If display jumps to approx. 143.0 °C:
- Press -> button.
- Press buttons -0- and -6- for "End output" function and confirm input with -Q- button.
- Switch off ignition.
- Replace Engine Coolant Temperature (ECT) sensor -G62- with Engine Coolant Temperature (ECT) sensor -G2-, item 28.
- Check DTC Memory, if necessary, repair any malfunctions and then Erase DTC Memory.
- Read readiness code. If DTC memory has been erased or Motronic Engine Control Module (ECM) -J220- was disconnected from battery positive, readiness code must be generated again.

If display remains at approx. -48.0°C:
- Press -> button.
- Press buttons -0- and -6- for "End output" function and confirm input with -Q- button.
- Switch off ignition.
- Check wiring using Electrical Wiring Diagram.

Continuation of check when display approx. 143.0°C:






- Disconnect 4-pin connector from Engine Coolant Temperature (ECT) sensor -G62- with Engine Coolant Temperature (ECT) sensor -G2- -arrow-.

If display jumps to approx. -48. °C:
- Press -> button.
- Press buttons -0- and -6- for "End output" function and confirm input with -Q- button.
- Switch off ignition.
- Replace Engine Coolant Temperature (ECT) sensor -G62- with Engine Coolant Temperature (ECT) sensor -G2-, item 28.
- Check DTC Memory, if necessary, repair any malfunctions and then Erase DTC Memory.
- Read readiness code. If DTC memory has been erased or Motronic Engine Control Module (ECM) -J220- was disconnected from battery positive, readiness code must be generated again.

If display remains at approx. 143.0°C:
- Press -> button.
- Press buttons -0- and -6- for "End output" function and confirm input with -Q- button.
- Switch off ignition.
- Check wiring using Electrical Wiring Diagram.

Checking wiring
- Remove inner plenum chamber cover, left.






- Connect VAG 1598/31 test box to control module wiring harness. Motronic Engine Control Module (ECM) -J220- is not connected by this action.






- Disconnect 4-pin connector from Engine Coolant Temperature (ECT) sensor -G62- with Engine Coolant Temperature (ECT) sensor -G2- -arrow-.






- Check wire for open circuit between test box and 4-pin connector using Electrical Wiring Diagram.
- terminal 3 + Socket 93
- terminal 4 + Socket 108
Wire resistance: max. 1.5 Ohms

- Check wiring between test box and 4-pin connector terminal 3 for short circuit to wire terminal 4 and to vehicle Ground (GND) using Electrical Wiring Diagram.
- terminal 3 + socket 108
- terminal 3 + vehicle Ground (GND)
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- terminal C (signal) and D (Ground).






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

Examples:
- 30 °C is in range A and corresponds to a resistance of 1.5 to 2.0 kOhms
- 80 °C is in range B and corresponds to a resistance of 275 to 375 Ohms

If the specification is not obtained:
- Replace Engine Coolant Temperature (ECT) sensor -G62- with Engine Coolant Temperature (ECT) sensor -G2-, item 28.
- Check DTC Memory, if necessary, repair any malfunctions and then Erase DTC Memory.
- Read readiness code. If DTC memory has been erased or Motronic Engine Control Module (ECM) -J220- was disconnected from battery positive, readiness code must be generated again.

If there is no malfunction in the wiring and the resistance measurement values are OK:
- Replace Motronic Engine Control Module (ECM) -J220-.
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