Engine Coolant Temperature (ECT) sensor -G62-, checking

WARNING: This page is about a different car, the 2006 Audi A4, 2005 Audi A4, 2004 Audi A4, 2003 Audi A4, and 2002 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Identifying Special Tools - Engine Coolant Temperature (ECT) Sensor -G62-, Checking

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Special tools and equipment

VAG1526 A
VAG1594 A
VAG1598/31
VAS5051 with VAS5051/1

Installation location. Refer to Component locations, overview

Test requirements:

Engine cold

Test sequence

Connect testing and information system VAS5051. Refer to Vehicle diagnostic, testing and information system VAS5051, connecting and select functions and select vehicle system "01 - Engine electronics" in selection. Engine must be running at idling speed.

Fig 2: Diagnostic System VAS 5051: Display

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Display on VAS5051:

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

Fig 3: Diagnostic System VAS 5051: Display

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Display on VAS5051:

1 - Enter display group

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

Fig 4: Diagnostic System VAS 5051: Display

Courtesy of VOLKSWAGEN UNITED STATES, INC.

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:

Fig 5: Disconnecting Electrical Harness Connector At Engine Coolant Temperature (ECT) Sensor -G2-/-G62-

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Disconnect connector -2- at Engine Coolant Temperature (ECT) sensor -G2-/-G62-.

Fig 6: Engine Coolant Temperature Sensor G62 Terminals

Courtesy of VOLKSWAGEN UNITED STATES, INC.

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 7: Resistance Values Graph

Courtesy of VOLKSWAGEN UNITED STATES, 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

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. Refer to Wiring and component check with test box VAG 1598/31 .

Fig 8: Coolant Temperature Sensor Terminals

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Check for open circuit and short to positive or ground in following wiring connections:

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. Refer to Engine Control Module (ECM) (without metal anti-theft housing), replacing .