Test sequence

• Connect testing and information system VAS5051. See VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS5051, CONNECTING AND SELECTING FUNCTIONS . Select vehicle system "01 - Engine electronics". Engine must be running at idling speed.

Display on VAS5051:

Fig 1: Identifying Display On VAS5051 - ECT Sensor Checking (1 Of 3)

Courtesy of AUDI OF AMERICA, INC.

• Under -1- select diagnostic function "08 - Read measured value block".

Display on VAS5051:

Fig 2: Identifying Display On VAS5051 - ECT Sensor Checking (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 VAS5051:

Fig 3: Identifying Display On VAS5051 - ECT Sensor Checking (3 Of 3)
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• Check indication in display field -3-.
  DISPLAY GROUP 004: COOLANT TEMPERATURE WITH ENGINE IDLING
  
  

  	Display zones
  	1	2	3	4
  Display group 004: Coolant temperature with engine idling
  Display	xxxx rpm	xx.x V	xxx.x °C	xxx.x ° C
  Display	Engine speed	Battery voltage	Coolant temperature	Intake air temperature
  Range			-48.0 to 143.0 ° C
  Specif. value	xxxx rpm	12.0 to 15.0 V	The temperature reading should increase evenly	from ambient temperature up to 110 ° C

If display zone 3 shows an implausible value:

• Disconnect connector -2- at Engine Coolant Temperature (ECT) gauge/Engine Coolant Temperature (ECT) sensor -G2-/-G62-.
  Fig 4: Disconnecting Engine Coolant Temperature (ECT) Gauge/Engine Coolant Temperature (ECT) Sensor

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• Connect multimeter between terminals C and D of sensor to measure resistance.

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

  Fig 5: Identifying Engine Coolant Temperature (ECT) Gauge/Engine Coolant Temperature (ECT) Sensor Connecter Terminals

  Courtesy of AUDI OF AMERICA, INC.

Sample readings:

• 30 ° C corresponds to a resistance of 1500 to 2000 Ω
• 80 ° C corresponds to a resistance of 275 to 375 Ω

Fig 6: ECT Sensor Resistance Versus Temperature Range Graph

Courtesy of AUDI OF AMERICA, INC.

If specified value is not obtained:

• Replace coolant temperature sensor.

If specified value is obtained:

• Connect test box VAG1598/31 to wiring harness for engine control module; do not connect engine control module. See WIRING AND COMPONENT CHECK WITH TEST BOX VAG1598/31 .
  Fig 7: Identifying Engine Coolant Temperature (ECT) Gauge/Engine Coolant Temperature (ECT) Sensor Harness Connecter Terminals

  Courtesy of AUDI OF AMERICA, INC.
• Check for open circuit and short to positive or short to ground in following wiring connections:
  ECT SENSOR CIRCUIT TEST: OPENS/SHORTS
  
  

  Connector terminal	Test box VAG1598/31 Socket
  3	108
  4 (signal)	93

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

If no wiring malfunciton is detected:

• Replace engine control module. See ENGINE CONTROL MODULE (ECM), REPLACING .