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

Intake Air Temperature (IAT) Sensor -G42-, Checking

Special tools and equipment
- VAG1551 scan tool or VAG1552 mobile scan tool with VAG1551/3B cable
- VAG1598/31 test box
- VAG1526 hand multimeter or VAG1715 multimeter
- VAG1594 adapter set
- Wiring diagram
- Chilling spray (commercially available)

Test sequence
- Connect VAG1551 scan tool (VAG1552). Switch ignition on and select engine control module with "Address word" 01. (Connecting scan tool and selecting engine control module). Refer to "VAG1551 Scan Tool Tools and Equipment

Indicated on display:


Rapid data transfer HELP
Select function XX


- Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

Indicated on display:


Read measured value block HELP
Input display group number XXX


- Press keys 0, 0 and 4 for "Display group number 4" and confirm entry with Q key.

Indicated on display: (1 to 4 = Display zones)


Read measured value block 4 ->
1 2 3 4


- Read off intake air temperature value in display zone 4.
Specification: approx. ambient temperature

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







If the specification is obtained:







- Remove Intake Air Temperature (IAT) sensor. Attach connector again.
- Note intake air temperature value in display zone 4.
- Spray sender with commercial chilling agent while observing temperature value. Temperature value must decrease.
- Press -> key.
- Press keys 0 and 6 for function "End output" and confirm entry with Q key.

Continuation of check when display reads approx. -48 °C:







- Pull connector -1- off Intake Air Temperature (IAT) sensor (G42) -2-.
- Bridge connector contacts using aux. cables from VAG1594 and observe display.

If display jumps to approx. 143 °C:
- Press -> key.
- Press keys 0 and 6 for the function "End output" and confirm entry with Q key.
- Switch ignition off.
- Replace Intake Air Temperature (IAT) sensor (G42).
- Check DTC Memory, if necessary, repair any malfunctions and then Erase DTC Memory,Checking and Erasing DTC Memory. Refer to "Monitors, Trips and/or Drive Cycle/ Reading Readiness Code" Testing and Inspection
- Read readiness code. If DTC memory has been erased or engine control module was disconnected from permanent positive, readiness code must be generated again: Refer to "Monitors, Trips and/or Drive Cycle/ Reading Readiness Code" Testing and Inspection
Engine code AWW, Refer to "Monitors, Trips and/or Drive Cycle/Generating Readiness Code" Testing and Inspection
Engine code AWP, Refer to "Monitors, Trips and/or Drive Cycle/Generating Readiness Code" Testing and Inspection

If display remains at approx. -48 °C:
- Press -> key.
- Press keys 0 and 6 for function "End output" and confirm entry with Q key.
- Switch ignition off.
- Check wiring using wiring diagram.

Continuation of check when display reads approx. 143 °C:







- Pull connector -1- off Intake Air Temperature (IAT) sensor (G42) -2-.

If display jumps to approx. -48 °C:
- Press -> key.
- Press keys 0 and 6 for function "End output" and confirm entry with Q key.
- Switch ignition off.
- Replace Intake Air Temperature (IAT) sensor (G42).
- Check DTC Memory, if necessary, repair any malfunctions and then Erase DTC Memory,Checking and Erasing DTC Memory. Refer to "Displaying and Reading Trouble Codes/With Manufacture Scan Tool/Check DTC Memory (Function 02)" Testing and Inspection
- Read readiness code. If DTC memory has been erased or engine control module was disconnected from permanent positive, readiness code must be generated again: Refer to "Monitors, Trips and/or Drive Cycle/ Reading Readiness Code" Testing and Inspection
Engine code AWW, Refer to "Monitors, Trips and/or Drive Cycle/Generating Readiness Code" Testing and Inspection
Engine code AWP, Refer to "Monitors, Trips and/or Drive Cycle/Generating Readiness Code" Testing and Inspection

If display remains at approx. 143 °C:
- Press -> key.
- Press keys 0 and 6 for function "End output" and confirm entry with Q key.
- Switch ignition off.
- Check wiring using wiring diagram.

Checking wiring







- Connect VAG1598/31 test box to control module wiring harness. The engine control module remains disconnected.







- Pull connector -1- off Intake Air Temperature (IAT) sensor (G42) -2-
- Check wiring between test box and 2-pin connector -1- for open circuit using wiring diagram.
Contact 1+socket 85
Contact 2+socket 108
Wire resistance: max. 1.5 Ohm
- Additionally check both wires for short to battery positive.

If no fault in wire is detected:







- Perform resistance measurement on Intake Air Temperature (IAT) sensor -2- (G42).







- Scale A shows resistance values for temperature range 0 to 50 °C and scale B the values for temperature range 50 to 100 °C.
Examples:
- 30 °C is in range A and corresponds to a resistance of 1.5 to 2.0 kOhm
- 80 °C is in range B and corresponds to a resistance of 275 to 375 Ohm

If the specification is not obtained:
- Replace Intake Air Temperature (IAT) sensor (G42).
- Check DTC Memory, if necessary, repair any malfunctions and then Erase DTC Memory,Checking and Erasing DTC Memory. Refer to "Displaying and Reading Trouble Codes/With Manufacture Scan Tool/Check DTC Memory (Function 02)" Testing and Inspection
- Read readiness code. If DTC memory has been erased or engine control module was disconnected from permanent positive, readiness code must be generated again: Refer to "Displaying and Reading Trouble Codes/With Manufacture Scan Tool/Check DTC Memory (Function 02)" Testing and Inspection
Engine code AWW, Refer to "Monitors, Trips and/or Drive Cycle/Generating Readiness Code" Testing and Inspection
Engine code AWP, Refer to "Monitors, Trips and/or Drive Cycle/Generating Readiness Code" Testing and Inspection

If there is no fault in the wiring and the resistance measurement values are OK.:
- Replace engine control module.