With Generic Scan Tool
Intake Air Temperature (IAT) Sensor -G42-, Checking
Recommended special tools and equipment
- VAG1526A hand multimeter
- VAG1594A connector test kit
- VAG1598/31 test box
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 internal resistance
- Connect multimeter at sensor for resistance measurement.
Specified values
Temperature degree C Resistance k Ohm
-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 (item 17).
Checking wire connections
- Connect test box to wiring harness of Engine Control Module (ECM); ECM is not connected.
- 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 Ohm
- Also check wires for short circuit to each other as well as to B+ and Ground (GND).
- Specified value: Infinite Ohm (no continuity)
- If necessary, repair wire connection.
If no malfunctions are found in wires:
- Replace Mass Air Flow (MAF) sensor -G70-, see -item 25-.
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".
2 - If necessary, erase DTC memory, see "Mode 4: Reset/erase diagnostic data".
3 - Generate readiness code. With Generic Scan Tool
- End diagnosis and switch ignition off.