Air Temperature Sensor ( Ambient / Intake ): Testing and Inspection

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







Special tools and workshop equipment required

- V.A.G 1526 A.
- V.A.G 1594 A.
- V.A.G 1598/31.
- VAS 5051 with VAS 5051/1.

Test 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. Connecting VAS 5051 Scan Tool

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-.

Display Group 004:

- 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. Wiring and Component Testing Using VAG1598/31 Test Box







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

Connector Test box VAG 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:

Check sensor:







- Connect multimeter to sensor to measure resistance.

Specifications:

Temperature degree 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-.