Test sequence

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

Display on VAS5051:

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

Display on VAS5051:

1 - Enter display group

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

Display on VAS5051:

• Check indication in display field -3-.

	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) sensor -G2-/-G62-.
Fig 4: Disconnecting Connector At Engine Coolant Temperature (ECT) Sensor
Courtesy of AUDI OF AMERICA, INC.
• Connect multimeter between terminals C and D of sensor to measure resistance.
Fig 5: Identifying Engine Coolant Temperature Sensor Terminals
Courtesy of AUDI OF AMERICA, INC.

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.

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 Graph
Courtesy of AUDI OF AMERICA, INC.

If specified value is not attained:

• Replace engine coolant temperature sensor.

If specified value is attained:

• 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 VAG 1598/31 .
• Check for open circuit and short to positive or ground in following wiring connections:
  Fig 7: Identifying Engine Coolant Temperature (ECT) Sensor Harness Connector Terminals

  Courtesy of AUDI OF AMERICA, INC.
  CONNECTOR TERMINAL 3, 4 & SOCKET 108, 93 (ECT SENSOR)
  
  

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

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

  If no wiring malfunction is detected:

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