Intake Air Temperature (IAT) Sensor -G42-, Checking

Intake Air Temperature (IAT) Sensor -G42-, Checking







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 information system with VAS 5051/1 B Adapter

Work sequence
- Connect vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01 -Engine electronics" in selection. Engine must be running at idle.







Display on VAS 5051:
- Under -1- select diagnostic function "08 - Read measured value block".







Display on VAS 5051:
1 - Display group input
- Enter "004" for "display group number 004" in zone -2- and confirm entry by pressing - Q- button.







Display on VAS 5051:
- Check Intake Air Temperature (IAT) sensor in display zone -4-.







1) If a temperature is displayed which deviates greatly from the ambient temperature of the sensor, check sensor and sensor wiring for terminal resistances and open circuit.

- Exit function "08 - Read measured value block" by pressing <- button.

Checking wiring
- Disconnect connector to Intake Air Temperature (IAT) sensor -G42-.
- Connect test box V.A.G 1598/31 to wiring harness for ECM; do not connect ECM.







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

Connector Test box V.A.G 1598/31
terminal Socket
1 85
2 108

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

If no wiring problems are found:

Checking sensor







- Connect multimeter to sensor to measure resistance.

Specifications

Temperature degrees C Resistance k Ohm
-20 approx. 13.8
0 approx. 5.5
20 approx. 2.4
40 approx. 1.1
60 approx. 0.6

If the specified values are not obtained:
- Replace Intake Air Temperature (IAT) sensor -G42-.