With Generic Scan Tool

Intake Air Temperature (IAT) Sensor, Checking

Recommended special tools and equipment
- V.A.G1526 multimeter or V.A.G1715 multimeter
- V.A.G1594 connector test kit
- Wiring diagram
- Chilling spray (commercially available)

Requirements







- The respective fuses of Motronic Engine Control Module (ECM) -J220- must be OK:
- Parking brake must be engaged or else daylight driving lights will be switched on.
- For vehicles with automatic transmission, selector lever must be in position -P- or -N-.

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







If specified value is not obtained:
- Continue test according to the following table:







If specified value is obtained:







- Remove Intake Air Temperature (IAT) Sensor -G42-. Plug connector back in.
- Remember the intake air temperature value.
- Spray the sensor with commercially available chilling spray while observing the temperature value. The temperature should 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 Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

Continuation of test if indication is approx. -40 degrees C:







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

If indication jumps to approx. 143 degrees C:
- End diagnosis and switch ignition off.
- Replace Intake Air Temperature (IAT) Sensor -G42-
- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

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

Continuation of test if indication is approx. 143 degrees C:







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

If indication jumps to approx. -40 degrees C:
- End diagnosis and switch ignition off.
- Replace Intake Air Temperature (IAT) Sensor -G42-
- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

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

Checking wiring
- Connect test box to control module wiring harness. Test Box, Connecting For Wiring Test







- Disconnect connector -1- from Intake Air Temperature (IAT) Sensor -G42- -2-.
- Check wires between test box and 2-pin connector -1- for open circuit according to wiring diagram.
Terminal 1 + socket 85
Terminal 2 + socket 108
Wire resistance: max: 1.5 Ohms

- Check wires for short circuit to each other, to vehicle Ground (GND) and to B+.
Specified value: Infinite Ohms

If no malfunctions are found in wire:







- Measure resistance at Intake Air Temperature (IAT) Sensor -G42-.







Range A displays resistance values for the temperature range of 0 to 0.50 degrees C, range B displays resistance values for the temperature range of 50 to 100 degrees C.

Read-out examples:
- 30 degrees C is in range A and corresponds to a resistance of 1.5 to 2.0 k Ohms
- 80 degrees C is in range B and corresponds to a resistance of 275 to 375 Ohms

If specified value is not obtained:
- Replace Intake Air Temperature (IAT) Sensor -G42-
- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

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