With Generic Scan Tool

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

Recommended special tools and equipment







- VAG1526A multimeter
- VAG1594A connector test kit
- VAG1598/31 test box

NOTE: Intake Air Temperature (IAT) Sensor -G42- is integrated in Mass Air Flow (MAF) Sensor -G70-.

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

Checking function
- Connect diagnostic tester. Diagnostic Tester, Connecting
- Start engine and let run at idle.
- In diagnostic function "33 - OBD", select "Mode 1: Checking measuring 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.

If indications do not resemble description:

Checking wire connections







- Disconnect harness connector -arrow- at Mass Air Flow (MAF) sensor.
- Connect test box to wiring harness of Engine Control Module (ECM); ECM is not connected. Text Box, Connecting For Wiring Test







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

Harness connector Test box
Terminal Socket
5 26

- Specified value: Wire resistance max 1.5 Ohm

- Also check wires for short circuit to each other as well as to B+ and Ground (GND).
- Specified value: infinity Ohm (no continuity)

- If necessary, repair wire connection.

If no malfunctions are found in wires:
- Replace Mass Air Flow (MAF) sensor -G70- -item 2-.

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". Diagnostic Mode 3: Check DTC Memory
2 - If necessary, erase DTC memory, "Mode 4: Reset/erase diagnostic data". Diagnostic Mode 4: Check Reset/Erase Diagnostic Data
3 - Generate readiness code. Readiness Code, Generating

- End diagnosis and switch ignition off.