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

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







Special tools and equipment
- VAG1526A or Fluke 83 Multimeter
- VAG1594A Connector test kit
- VAG1598/31 Test box
- VAS5051 Vehicle diagnosis, testing and information system with VAS5051/1 Adapter

Work sequence
- Connect VAS5051 tester, Vehicle Diagnostic, Testing and Information System VAS 5051, Connecting and Selecting Functions and select vehicle system "01 - Engine electronics". Engine must run at idle.







Display on VAS5051:
- Select diagnostic function "08 - read measured value block" in selection -1-.







Display on VAS5051:
1 - Enter display group. Max. input value = 255
- Select function "004" in button field -2- for "display group number 004" and press Q button to confirm input.







Display on VAS5051:
- Check IAT sensor in display field 4.







- Press <- button to end function "08 - Read measuring value block".

Checking wiring connections
- Connect VAG1598/31 test box at wiring harness to Engine Control Module (ECM) but do not connect ECM. Scan Tool Testing and Procedures







- Disconnect connector -1- at Intake Air Temperature (IAT) sensor -G42- (item -2-).







- Check following wiring connections for open circuit and short circuit to Ground (GND) and B+:

Harness connector Terminal VAG1598/31 test box Socket
1 85
2 108

- Check both wires to each other for short circuit.
- Repair open circuit in wiring or short circuit if necessary.

If no malfunctions are found in wires:
- Check resistance of intake air temperature sensor.

Checking sensor







- Connect multimeter at sensor for resistance measurement.

Specified values

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

If specified value is not obtained:
- Replace Intake Air Temperature (IAT) sensor -G42-.