Test sequence

• Connect vehicle diagnostic, testing and information system VAS 5051. See VAS 5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM, CONNECTING AND SELECTING FUNCTIONS . Select vehicle system "01 - Engine electronics" in selection. Engine must be run at idle.

  Display on VAS 5051:

  Fig 1: Identifying Display On VAS 5051 - Engine Coolant Temperature Sensor (1 Of 3)

  Courtesy of AUDI OF AMERICA, INC.
• Under -1- select diagnostic function "08 - Read measured value block".

  Display on VAS 5051:

  Fig 2: Identifying Display On VAS 5051 - Engine Coolant Temperature Sensor (2 Of 3)

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

Display on VAS 5051:

Fig 3: Identifying Display On VAS 5051 - Engine Coolant Temperature Sensor (3 Of 3)
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• Check Engine Coolant Temperature (ECT) sensor -G62- in display zone -3-.

If display zone 3 shows an implausible value:

• Disconnect Engine Coolant Temperature (ECT) sensor connector at -G2- / -G62- -arrow-.
Fig 4: Disconnecting Engine Coolant Temperature Sensor Connector
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• Connect multimeter between terminals C and D of sensor to measure resistance.
  Fig 5: Identifying ECT Sensor Connector Terminals

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

  Sample readings:

  • 30 °C corresponds to a resistance of 1500...2000Ω
  • 80 °C corresponds to a resistance of 275..375Ω
  Fig 6: Identifying ECT Sensor Temperature Versus Resistance

  Courtesy of AUDI OF AMERICA, INC.

If specified value is not obtained:

• Replace Engine Coolant Temperature (ECT) sensor -G62-.

If specified value is obtained:

• Connect test box V.A.G 1598/31 to wiring harness for ECM; do not connect directly to the ECM. See ELECTRICAL TESTING USING VAG1598/31 TEST BOX .
• Check for open circuit, short to positive, or short to ground in following wiring connections:
Fig 7: Identifying ECT Sensor Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

• Test for short circuits between two wires.
• Repair any open/short circuit as necessary.

If no wiring problems are found:

• Replace ECM. See ENGINE CONTROL MODULE (ECM) (WITHOUT METAL ANTI-THEFT HOUSING), REPLACING .