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: Engine Coolant Temperature (ECT) Sensor -G62-, Checking

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Special tools and workshop equipment required

V.A.G 1526 A Multimeter
V.A.G 1594 A Connector test kit
V.A.G 1598/31 Test box
VAS 5051 Vehicle diagnostic, testing and vehicle information system with VAS 5051/1 Adapter

Component location → Component locations, overview

Requirements

Engine cold

Work sequence

Connect vehicle diagnostic, testing and information system VAS 5051. Refer to VAS 5051 vehicle diagnostic, testing and information system, connecting and selecting functions and select vehicle system "01 -Engine electronics" in selection. Engine must be run at idle.

Fig 2: Diagnostic System VAS 5051: Display

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Display on VAS 5051:

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

Fig 3: Diagnostic System VAS 5051: Display

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Display on VAS 5051:

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

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Display on VAS 5051:

Check Engine Coolant Temperature (ECT) sensor -G62- in display zone -3-.

	Display zones
	1	2	3	4
Display group 004: Coolant temperature with engine at idle
Display	xxxx rpm	xx.x V	xxx.x ° C	xxx.x ° C
Display	Engine speed	Battery voltage	Coolant temperature	Intake Air Temperature (IAT)
Range			-48.0...143.0 ° C
Specified value	xxxx rpm	12.0 to 15.0 volts	The temperature reading should increase evenly	from ambient temperature up to 110 ° C

If display zone 3 shows an implausible value:

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

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

Fig 6: Engine Coolant Temperature Sensor G62 Terminals

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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...50 ° C and range B shows the values for temperature range 50...100 ° C.

Fig 7: Resistance Values Graph

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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 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 ECM. Refer to Electrical testing using VAG1598/31 test box .

Fig 8: Coolant Temperature Sensor Terminals

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

Connector Terminal	Test box V.A.G 1598/31 Socket
3	108
4 (signal)	93

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

If no wiring problems are found:

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