Air Temperature Sensor ( Ambient / Intake ): Testing and Inspection
Intake Air Temperature (IAT) Sensor -G42-, Checking
Recommended special tools and equipment
- V.A.G 1526A multimeter
- V.A.G 1594A connector test kit
- V.A.G 1598/31 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.
- 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 wire connections
- Disconnect electrical harness connector -4- at Mass Air Flow (MAF) Sensor -G70-.
NOTE:
- Depicted in illustration with air filter cover removed.
- Disregard the other items as well as the arrow.
- 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 26
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 see "Mode 3: Check DTC memory". Mode 3: Check DTC Memory
2. If necessary, erase DTC memory see "Mode 4: Reset/erase diagnostic data". Mode 4: Reset/Erase Diagnostic Data
3. Generate readiness code. Readiness Code, Generating
- End diagnosis and switch ignition off.