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

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

Location of sensor: in intake manifold, on left in direction of travel

Work sequence
- Connect vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01 - Engine electronics" from list. Engine must be idling. Connecting VAS 5051 Scan Tool

Indicated on VAS 5051:







- From list -1- select diagnostic function "08 - Reading measured value block".

Indicated on VAS 5051:







1 - Enter display group
- Use keypad -2- to enter "004" for "Display group number 004" and confirm by touching Q key.

Indicated on VAS 5051:







- Check display in zone -4-.

Display Group 004:

NOTE: With engine cooled down, displays in zones 3 (coolant temperature) and 4 (intake air temperature) must be roughly equal.

- Terminate function "08 - Reading measured value block" by touching <- key.

Checking wiring
- Remove air cleaner housing.
- Switch off ignition.
- Connect test box V.A.G 1598/31 at wiring harness to engine control module. Actual engine control module is not to be connected. Wiring And Component Check Using Test Box V.A.G 1598/31
- Disconnect connector to Intake Air Temperature (IAT) sensor -G42-.







- Check wiring for mutual short circuit:

2-pin connector at Test box V.A.G
wiring harness, socket 1598/31, socket
1 108

Specification: Infinite Ohm (no connection)







- Check for open circuit and short to Ground/positive in following wiring:

2-pin connector at Test box V.A.G
wiring harness, socket 1598/31, socket
1 26
2 108

Resistance: max.1.5 Ohm

- Eliminate open circuit in wiring/short circuit if necessary.

If no fault is found in wiring:
- Replace Intake Air Temperature (IAT) sensor -G42-.