Intake Air Temperature Sensor, Checking
INTAKE AIR TEMPERATURE SENSOR, CHECKING
Special tools, testers and auxiliary items
- VAG 1551 Scan Tool (ST) or vehicle system tester VAG 1552 with VAG 1551/3 adapter cable
- VAG 1598/18 test box
- Multimeter (Fluke 83 or equivalent)
- VW 1594 connector test kit
- Wiring diagram
- Chilling spray (commercially available)
Test sequence
- Connect VAG 1551 scan tool (VAG 1552) and insert "Engine Electronics" address word 01. Carry out selection with ignition switched on. Refer to "On-Board Diagnostic". Testing and Inspection
Indicated on display
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -8- to select "Read Measuring Value Block" function 08.
- Press -Q- button to confirm input.
Indicated on display
Read measuring value block HELP
Input display group number XXX
- Press -0-, -0- and -3- to input display group number 003.
- Press -Q- button to confirm input.
Indicated on display (1, 2, 3 and 4 = Display fields)
Reading measured value block 3 ->
1 2 3 4
NOTE: If something different is indicated on the display:
See Scan tool operating instructions.
Functional Check
- Read intake air temperature value in display field 4.
Continuation Of Check When Display = 19.6 °C
- Switch ignition off.
- Connect VAG 1598/18 test box to ECM wiring harness.
- Disconnect 2-Pin harness connector -1- from intake air temperature sensor G72 -2-.
- Check wiring for open circuits between test box and 2-pin connector, according to wiring diagram.
- Terminal 1 and test box socket 36
- Terminal 2 and test box socket 33
- Wire resistance: Max. 1.5 Ohms
- Check wiring between ECM connector and 2-pin connector terminal 2 for short circuit to terminal 1 and/or chassis ground, according to wiring diagram.
- Terminal 2 and test box socket 36
- Specification: Infinity Ohms (continuity)
- Additionally check wiring for short to battery positive (B+).
- Specification: Infinity Ohms (no continuity)
If no wiring malfunction is detected:
- Measure resistance on intake air temperature sensor G72 terminals 1 and 2.
Resistance Specifications
The diagram is valid for engine coolant temperature sensor G62 and intake
air temperature sensor G72.
A - resistance values for the temperature range 0 ° - 50 °C (32 ° - 122 °F)
B - resistance values for the temperature range 50 ° - 100 °C (122 ° - 212 °F)
Examples:
- 30 °C corresponds to a resistance value of 1500 - 2000 Ohms
- 80 °C corresponds to a resistance value of 275 - 375 Ohms
If the specification is not attained:
- Replace intake air temperature sensor G72.
Continuation of check when display = ambient temperature
- Remove intake air temperature sensor G72 (harness connector remains connected).
- Note intake air temperature value in display field 4.
- Spray sensor with chilling spray (commercially available) while observing temperature display.
- Temperature value must decrease.
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06.
- Press -Q- button to confirm input.