Intake Air Temperature (IAT) Sensor, Checking

Intake Air Temperature (IAT) Sensor, Checking

- Connect VAG1551 or VAG1552 Scan Tool (ST) and press buttons -0- and -1- to insert "Engine Electronics" address word 01. [1][2]Scan Tool Connecting and Initial Checks

Indicated on display


Rapid data transfer HELP
Select function XX


- Press buttons -0- and -8- to select "Read Measuring Value Block" function 08, and press -Q- button to confirm input.

Indicated on display


Read Measuring Value Block
Input display group number XXX


- Press buttons -0-, -0- and -3- to input display group number 3 (003), and press -Q- button to confirm input.

Indicated on display


Read Measuring Value Block 3 ->
1 2 3 4


- Check specified values for basic functions at engine idle speed (display field 4):







- Press -> button to advance program sequence.
- Press buttons -0- and -6- to select "End Output" function 06, and press -Q- button to confirm input.

If the ECM-calculated replacement value (20 °C) is displayed:
- Disconnect IAT sensor harness connector.







- Connect multimeter US 1119 (Fluke 83 or equivalent) and measure resistance across of IAT sensor terminals.

Specified values (vs. sensor temperature):
- At 0 °C: approx. 14.80 - 18.00 kohms
- At 20 °C: approx. 5.60 - 6.80 kohms
- At 40 °C: approx. 2.30 - 2.90 kohms
- At 60 °C: approx. 1.00 - 1.40 kohms

If resistance values differ from specified values:
- Replace IAT sensor -G42-.
- Check readiness code. If DTC memory has been erased, generate new readiness code.
Readiness Code Reading
Readiness Code, Generating

- If resistance values are OK:
- Check wiring between ECM as follows:
- Connect VAG1598/19 test box to ECM harness connector. Connecting VAG 1598/19 Test Box






- Check wiring for open circuit or short circuit to B+ or Ground between 2-pin IAT sensor connector and ECM.

2-pin IAT sensor connector terminal VAG1598/19 test box socket (ECM terminal)
1 A22
2 A19







If there are no wiring or sensor malfunctions:
- Replace ECM and generate new readiness code. Readiness Code, Generating