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

Intake Air Temperature (IAT) Sensor -G42, Checking

Location of sensor (mass air flow sensor and intake air temperature sensor are combined as one component in air filter).

- Connect vehicle diagnostic, testing and information system VAS5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". When doing this the ignition must be switched on. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAS5051 or VAG1551" Testing and Inspection

Indicated on display


Rapid data transfer HELP
Select Function XX


- Press buttons -0- and -8- to select function "Read Measuring Value Block" and confirm entry with -Q- button.

Indicated on display


Read Measuring Value Block HELP
Input Display Group Number XXX


- Press buttons -0-, -0- and -4- to select Display Group 4 and confirm entry with -Q- button.

Indicated on display: (1 - 4 = display fields)


Read Measuring Value Block 4 ->
1 2 3 4







- Check display value for intake air temperature sensor (display field 4):

Checking wiring
- Switch ignition off.
- Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to the engine control module itself. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG1598/31 Test Box" Testing and Inspection

- Disconnect harness connector from mass air flow sensor.







- Check for short circuit between wires:

5-pin connector VAG1598/31 test box
on wiring harness, socket
1 27

Specification: infinity Ohms (open circuit)







- Check for open circuit and short to B+ or Ground (GND) in the following wiring connections:

5-pin connector VAG1598/31 test box
on wiring harness, socket
1 85
3 27

Resistance in wiring: max. 1.5 Ohms

- Repair any open/short circuit as necessary.

If no wiring malfunction is detected:
- Replace Intake Air Temperature (IAT) sensor -G42.
- Display readiness code. The readiness code must be generated if the DTC memory was erased.
Refer to "Monitors, Trips and/or Drive Cycle (Readiness Codes)/Checking Readiness Code" Testing and Inspection
Refer to "Monitors, Trips and/or Drive Cycle (Readiness Codes)/Generating Readiness Code" Testing and Inspection