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Home >> Volkswagen >> 2005 >> New Beetle (1C1) L4-1.8L Turbo (AWP) >> Repair and Diagnosis >> Powertrain Management >> Sensors and Switches - Powertrain Management >> Sensors and Switches - Computers and Control Systems >> Air Temperature Sensor ( Ambient / Intake ) >> Testing and Inspection

Air Temperature Sensor ( Ambient / Intake ): Testing and Inspection



Intake Air Temperature (IAT) Sensor, Checking

Recommended special tools and equipment
- VA.G 1526 multimeter or V.A.G 1715 multimeter
- V.A.G 1594 connector test kit
- Wiring diagram
- Chilling spray (commercially available)

Test requirements







- The respective fuses of Motronic Engine Control Module (ECM) -J220- must be OK.
- Parking brake must be engaged or else day time driving lights will be switched on.
- Ground (GND) connections between engine and chassis must be OK.
- For vehicles with automatic transmission, selector lever must be in -P-.

Function test (vehicles with engine code APH, AWP, AWV)
- Connect diagnostic tester.
- Switch ignition on.
- Under address word 33, select "Diagnostic mode 1: Check 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:
- Remember the intake air temperature value.







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







- Remove Intake Air Temperature (IAT) Sensor -G42-. Re-connect connector.
- Spray sensor with commercially available chilling spray while observing the temperature value. The temperature must decrease.
- End diagnosis and switch ignition off.

If the intake air temperature does not drop
- 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 2-pin connector from Intake Air Temperature (IAT) Sensor -G42- (arrow).







- 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 to control module according to wiring diagram.

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







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

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 to control module according to wiring diagram.

Check wires to control module
- Connect test box to control module wiring harness. connect test box for wiring test. Test Box, Connecting For Wiring Test







- Check wires between test box and 2-pin connector to Engine Control Module (ECM) 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.

Specified value: Infinite Ohms

- 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 found in wire:

Checking resistance







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







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 kohms
- 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-.

Function test (vehicles with engine code BKF, BNU)
- Connect diagnostic tester.
- Switch ignition on.
- Under address word 33, select "Diagnostic mode 1: Check measured values."
- Select 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:
- Remember intake air temperature value.
- Remove intake air hose between Mass Air Flow (MAF) sensor and throttle valve control module.







- Spray 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 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 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. 143 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 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 to control module according to wiring diagram % page 24-102.

Continuation of test if indication is approx. 143 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 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 to control module according to wiring diagram.

Check wires to control module
- Connect test box to control module wiring harness. connect test box for wiring test. Test Box, Connecting For Wiring Test







- Check wires between test box and 5-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram.

Terminal 1 + socket 26
Terminal 3 + socket 27

Wire resistance: max. 1.5 Ohms

- Check wires for short circuit to each other.

Specified value: Infinite Ohms

- 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 found in wire:

Checking resistance







- 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 kohms
- 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 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-.
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