Intake Air Temperature Sensor, Checking

Intake Air Temperature Sensor, Checking

Recommended Special Tools, Workshop Equipment, Testers, Measuring Instruments and Auxiliary Items
- V.A.G 1526 portable multimeter or V.A.G 1715 multimeter
- Adapter set V. A. G 1594
- Wiring diagram
- Chilling spray (commercially available)

Test Conditions
- The corresponding fuses of Motronic Engine Control Module (ECM) -J220- must be OK
- The parking brake must be applied, otherwise the daytime running lights are switched on.

Function Test
- Connect diagnostic tester. Diagnostic Tester, Connecting
- Switch ignition on.
- Under address word 33, select "Diagnostic mode 1: Checking measuring values."
- Select the measuring value "PID 15: Intake air temperature ".
- Check specified value of intake air temperature:







If the specification is not obtained:
- Perform the test according to the following table:







If the specification is obtained:
- Remove Intake Air Temperature (IAT) Sensor -G42-. Re-connect connector.
- Remember the intake air temperature value.
- Spray sensor with commercially available chilling spray and watch temperature value. Temperature value must decrease.
- End diagnosis and switch ignition off.

If the intake air temperature does not drop:
- Replace Intake Air Temperature (IAT) Sensor -G42-.
- Erase DTC memory of ECM. Diagnostic Mode 04 - Erase DTC Memory
- Generate readiness code. Generate Readiness Code

If Display Shows Approx. -40 degrees C:







- Disconnect connector -1 - from Intake Air Temperature (IAT) Sensor -G42- (- 2 -).
- Bridge terminals 1 + 2 of connector using the corresponding adapter cables and observe the indication on display.

If display jumps to approx. 143 degrees C:
- End diagnosis and switch ignition off.
- Replace Intake Air Temperature (IAT) Sensor -G42-.
- Erase DTC memory of ECM. Diagnostic Mode 04 - Erase DTC Memory
- Generate readiness code. Generate Readiness Code

If display stays at approx. -40 degrees C:
- End diagnosis and switch ignition off.
- Check wiring according to wiring diagram.

If Display Shows Approx. 143 degrees C:







- Disconnect connector -1 - from Intake Air Temperature (IAT) Sensor -G42- (- 2 -).

If display jumps to approx. -40 degrees C:
- End diagnosis and switch ignition off.
- Replace Intake Air Temperature (IAT) Sensor -G42-.
- Erase DTC memory of ECM. Diagnostic Mode 04 - Erase DTC Memory
- Generate readiness code. Generate Readiness Code

If display stays at approx. 143 degrees C:
- End diagnosis and switch ignition off.
- Check wiring according to wiring diagram.

Checking Wiring
- Connect test box to control module wiring harness.
- Check wires between test box and 2-pin connector for open circuit according to wiring diagram.

Terminal 1 + Socket 85
Terminal 2 + Socket 108







Wiring resistance: max. 1.5 Ohms

- Also check wires for short circuit to each other, to vehicle Ground (GND) and to B+.

Specification: Infinity Ohms

If no fault is detected in the wiring:







- Perform a resistance measurement on Intake Air Temperature (IAT) Sensor -G42-.







Area A shows resistance values for temperature range 0 to 50 degrees C, area B shows values for temperature range 50 to 100 degrees C.

Example:
- 30 degrees C is in area A and corresponds to a resistance of 1.5 to 2.0 k Ohms
- 80 degrees C is in area B and corresponds to a resistance of 275 to 375 Ohms

If the specification is not obtained:
- Replace Intake Air Temperature (IAT) Sensor -G42-.
- Erase DTC memory of ECM. Diagnostic Mode 04 - Erase DTC Memory
- Generate readiness code. Generate Readiness Code

If no malfunctions are detected in the wires and the resistance values are OK:
- Replace Motronic Engine Control Module (ECM) -J220-.