With Generic Scan Tool

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







Recommended special tools and equipment
- V.A.G1526A hand multimeter
- V.A.G1594A connector test kit
- V.A.G1598/31 test box

Test requirements:
- Fuses for engine electronics OK
- Ignition switched off.

Checking function
- Connect diagnostic tester. Connect Diagnostic Tester
- Start engine and let run at idle.
- In diagnostic function "33 - OBD", select "Mode 1: Checking measured values."
- Select the desired measuring value "PID 15: Intake air temperature".

Specified value: approx. ambient temperature

NOTE: If a temperature is indicated which differs greatly from ambient temperature of sensor, check sensor and sensor wires for contact resistances and open circuit.

- End diagnosis and switch ignition off.

If indications do not resemble description.

Checking internal resistance







- 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 values are not obtained:
- Replace Intake Air Temperature (IAT) sensor.

Checking wire connections
- Connect test box to wiring harness of Engine Control Module (ECM). ECM is not connected. Test Box, Connecting For Wiring and Component Test







- Check the following wire connection for open circuit according to wiring diagram.

Harness connector Terminal Test box Socket
1 85
2 108


Specified value: Wire resistance max 1.5 Ohms

- Check wires for short circuit to each other as well as to B+ and Ground (GND).
- Specified value: infinite Ohms (no continuity)

- If necessary, repair wire connection.

If no malfunctions are found in wires:
- Replace Mass Air Flow (MAF) sensor -G70-.

Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:
1. Check DTC memory. Mode 3: Check DTC Memory
2. If necessary, erase DTC memory. Mode 4: Reset/Erase Diagnostic Data
3. Generate readiness code. Readiness Code, Generating
- End diagnosis and switch ignition off.