Audi Workshop Service and Repair Manuals > A3 Mk1 > Power unit | Simos injection and ignition system (4-cylinder) | Ignition system, glow plug system | Checking ignition system | Checking coolant temperature sender G62

Test sequence

–	Connect vehicle diagnostic, testing and information system -VAS 5051- or fault reader -V.A.G 1551- and select engine electronics control unit by entering “address word ” 01. For this purpose, the engine must be running at idling speed.

Indicated on display:

–	Enter “08” for the function “Read measured value block” and confirm entry with the Q key.

Rapid data transfer HELP

Select function XX

Indicated on display:

–	Enter “004” for “Display group number 004” and confirm entry with the Q key.

–	Check display in display zone 3.

Reading measured value block Q

Enter display group number XXX

	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
Readout	Engine speed	Battery voltage	Coolant temperature	Intake air temperature
Specification	xxxx rpm	12.0...15.0 V	The temperature reading should increase evenly	From ambient temperature to 120 °C

If display zone 3 shows an implausible value:

–	Disconnect connector on coolant temperature sender.

–	Connect multimeter to contacts 3 and 4 of sender to measure resistance.

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

Sample readings:

t	30 °C corresponds to a resistance from 1500...2000 Ω

t	80 °C corresponds to a resistance from 275...375 Ω

If specification is not attained:

–	Replace coolant temperature sender.

If specification is attained:

–	Connect test box -V.A.G 1598/31- to wiring harness for engine control unit. Do not connect to the engine control unit itself.

–	Check for open circuit and short to positive or earth in the following wiring connections:

–	Check for short circuits between the two wires.

–	Rectify any open/short circuit as necessary. → Current flow diagrams, Electrical fault finding and Fitting locations

If no wiring fault is detected:

–	Renew engine control unit.

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