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

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

Special Tools and Equipment

- VAG1526A
- VAG1594A
- VAG1598/31
- VAS5051 with VAG5051/1
- or
- VAG1551 with VAG1551/3B

Test sequence
- Connect VAS5051 tester or VAG1551 scan tool and select the control module for engine electronics using "address word". Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks", Testing and Inspection
Ignition must remain switched on for this.

When indicated on display:

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -8- to select "Read Measuring Value Block" and press -Q- button to confirm input.

When indicated on display:

Read Measuring Value Block Q
Input display group number XXX

- Press buttons -0-, -0- and -4- to select "display group number 004" and press -Q- button to confirm input.

Indicated on display:

Read Measuring Value Block 4 ->
1 2 3 4

- Check specified value for Intake Air Temperature (IAT) sensor in display field 4:

Checking wire connections
- Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. Refer to "Scan Tool Testing/Wire And Component Test Using VAG1598/31 Test Box", Testing and Inspection

- Check the following wire 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 or short circuit if necessary.

If no malfunctions are found in wire:

Check sensor:
- Disconnect connector from Intake Air Temperature (IAT) sensor.

- Connect multimeter at sensor for resistance measurement.

Specified values

Temperature °C Resistance kOhms
-20 approx. 13.8
0 approx. 5.5
20 approx. 2.4
40 approx. 1.1
60 approx. 0.6

NOTE:: If air temperature is in a range from 0 °C to 20 °C, the resistance value must be between 5 kOhms and 2.4 kOhms

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