Work sequence

• Connect vehicle diagnostic, testing and information system VAS 5051. See VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND SELECTING FUNCTIONS and select vehicle system "01 - Engine electronics" from list. Engine must be idling.

Indicated on VAS 5051:

Fig 1: Scan Tool VAS 5051 Display - Checking Engine Coolant Temperature (ECT) Sensor G62 (1 Of 3)

Courtesy of AUDI OF AMERICA, INC.

• From list -1- select diagnostic function "08 - Reading measured value block".

Indicated on VAS 5051:

Fig 2: Scan Tool VAS 5051 Display - Checking Engine Coolant Temperature (ECT) Sensor G62 (2 Of 3)

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1 - Enter display group

• Use keypad -2- to enter "004" for "Display group number 004" and confirm by touching Q key.

Indicated on VAS 5051:

Fig 3: Scan Tool VAS 5051 Display - Checking Engine Coolant Temperature (ECT) Sensor G62 (3 Of 3)

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• Check display in zone -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
  Significance	Engine speed	Battery voltage	Coolant temperature	Intake air temperature
  Operating range			-48.0...143.0 °C
  Specification	xxxx RPM	12.0...15.0 V	Temperature value must increase steadily	Between ambient temperature and 110 °C

If display in zone 3 is not realistic:

• Disconnect connector at Engine Coolant Temperature (ECT) sensor -G62-.
• Connect test box V.A.G 1598/31 at wiring harness to engine control module. Actual engine control module is not to be connected. See WIRING AND COMPONENT CHECK USING TEST BOX V.A.G 1598/31 .
• Check wiring from 4 -pin connector...
• ... to engine control module for open circuit and short to positive/Ground.
  ECT SENSOR CIRCUIT - OPEN CIRCUIT AND SHORT TO POSITIVE/GROUND
  
  

  4-pin connector at wiring harness, socket	Test box V.A.G 1598/31, socket
  3	108
  4	93

  Resistance: max. 1.5 ohms

• Eliminate open circuit in wiring/short circuit if necessary.

If no fault is found in wiring:

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

Readings:

Fig 4: ECT Sensor Temperature Versus Resistance Graph

Courtesy of AUDI OF AMERICA, INC.

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