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Home >> Volkswagen >> 2006 >> Touareg (7LA) V8-4.2L (AXQ) >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Testing and Inspection >> Component Tests and General Diagnostics >> Component Tests (VAG Code Tests) >> Intake Air Temperature (IAT) Sensor, Checking

Intake Air Temperature (IAT) Sensor, Checking



Intake Air Temperature (IAT) Sensor, Checking

NOTE: When servicing terminals in the harness connector for the Intake Air Temperature (IAT) sensor, use only gold-plated terminals.

Recommended special tools and equipment
- VAG1526 multimeter or VAG1715 multimeter
- VAG1594 connector test kit
- Wiring diagram
- Chilling spray (commercially available)

Test requirements







- Fuses in E-box (in plenum chamber, left) must be OK:
- Ground (GND) connections between engine and chassis 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 - P - position.

Function test
- Connect diagnostic tester.
- 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 duct for cylinder bank 1.
- Remember the intake air temperature value.







- Spray the sensor (arrow) with commercially available chilling spray and watch the temperature value. The temperature must decrease.
- End diagnosis and switch ignition off.

If the intake air temperature does not drop:
- Replace Mass Air Flow (MAF) Sensor - G70 -.

NOTE: The Intake Air Temperature (IAT) Sensor -G42- is a component of the Mass Air Flow (MAF) Sensor - G70 - and cannot be replaced individually.

- Erase DTC memory of Engine Control Module (ECM). Diagnostic Mode 04 - Erase DTC Memory
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

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







- Disconnect 5-pin connector from Mass Air Flow (MAF) Sensor - G70 - with Intake Air Temperature (IAT) Sensor -G42- arrow.







- Bridge terminals 1 + 3 of connector using the respective adapter cables while observing the indication on display.

If indication jumps to approx. 140 degrees C:
- End diagnosis and switch ignition off.
- Replace Mass Air Flow (MAF) Sensor - G70 -.

NOTE: The Intake Air Temperature (IAT) Sensor - G42 - is a component of the Mass Air Flow (MAF) Sensor - G70 - and cannot be replaced individually.

- Erase DTC memory of Engine Control Module (ECM). Diagnostic Mode 04 - Erase DTC Memory
- 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. 140 degrees C:







- Disconnect 5-pin connector from Mass Air Flow (MAF) Sensor - G70 - with Intake Air Temperature (IAT) Sensor - G42 - arrow.

If indication jumps to approx. -40 degrees C:
- End diagnosis and switch ignition off.
- Replace Mass Air Flow (MAF) Sensor - G70 -.

NOTE: The Intake Air Temperature (IAT) Sensor - G42 - is a component of the Mass Air Flow (MAF) Sensor - G70 - and cannot be replaced individually.

- Erase DTC memory of Engine Control Module (ECM). Diagnostic Mode 04 - Erase DTC Memory
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

If indication remains at approx. 140 degrees C:
- End diagnosis and switch ignition off.
- Check wires according to wiring diagram.

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







- Check wires between test box and 5-pin connector for open circuit according to wiring diagram.
Terminal 1+socket 26
Terminal 3 + socket 27

Wire resistance: max. 1.5 ohms

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

Specified value: infinity ohms.

- Erase DTC memory of Engine Control Module (ECM). Diagnostic Mode 04 - Erase DTC Memory
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

If no malfunctions are found in wire:







- Measure resistance at Intake Air Temperature (IAT) Sensor - G42 -, terminals 1 (signal) and 3 (Ground -GND-).







Range A displays resistance values for the temperature range of 0 to 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 Mass Air Flow (MAF) Sensor - G70 -.

NOTE: The Intake Air Temperature (IAT) Sensor - G42 - is a component of the Mass Air Flow (MAF) Sensor - G70 - and cannot be replaced individually.

- Erase DTC memory of Engine Control Module (ECM). Diagnostic Mode 04 - Erase DTC Memory
- 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-.
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