Intake Air Temperature (IAT) Sensor - G42-, Checking
Intake Air Temperature (IAT) Sensor -G42, Checking
- 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 VAS 5051/ VAG 1551 Scan Tool" 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 number 004" 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 field4):
Display Group 004:
Checking wiring:
- Switch ignition off.
- Connect test box VAG1598/31 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
- Check for open circuit in wiring between test box and 2 pin harness connector using wiring diagram.
Specification: max. 1.5 Ohms
Terminal on 2-pin Contact on control
harness Connector module connector or test box
1 85
2 108
- Check wiring for short circuits to each other between contacts 1 and 2 on 2-pin connector. Also test for short circuits to B+ or Ground (GND).
If no malfunction in wire is detected:
Checking sensor
- Measure resistance between contacts 1 (signal) and 2 (Ground GND)) on connector for Intake Air Temperature (IAT) sensor -G42.
Temperature ° C Resistance kOhms
-20 approx. 13.8
0 approx. 5.5
20 approx. 2.4
40 approx. 1.1
60 approx. 0.6
- If value does not match the specification, replace intake air temperature sensor.
- In order to install new sensor, the intake manifold must first be removed.