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

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

Special tools and equipment







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

Test sequence
- Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using "address word" 01. Engine must run at idle. [1][2]Scan Tool Connecting and Initial Checks

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
Enter 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:

Display Group 004:

Checking wire connections
- Connect VAG1598/31 test box at wiring harness to Engine Control Module (ECM), do not connect ECM [1][2]Scan Tool Connecting and Initial Checks







- Disconnect connector -1- at Intake Air Temperature (IAT) sensor -G42- (item no. 2).







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

Harness connector VAG1598/31 test box
Terminal 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 wires:

Check sensor:







- Connect multimeter at sensor for resistance measurement.

Specified values

Temperature °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.