Intake Air Temperature Sensor 2, Checking: Notes

Special tools and workshop equipment required 

• Multimeter.
• Wiring diagram.
• Cool spray (commercially available).

Test requirements 

• The Motronic Engine Control Module (ECM) - J220- fuses OK.
  Fig 1: Fuses On E-Box In Engine Compartment, Left Side

  Courtesy of AUDI OF AMERICA, LLC
• Battery voltage at least 12.5 volts.
• All electrical consumers such as, lights and rear window defroster, switched off.
• Vehicles with automatic transmission, shift selector lever into position "P" or "N".
• A/C switched off.
• Ground (GND) connections between engine/transmission/chassis OK.
• Ignition switched off.

Test procedure 

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK 

Start diagnosis 

-- Connect the scan tool.

-- Switch the ignition on.

-- Using the scan tool, check the intake air temperature:

Diagnostic text		Specified value
Intake Air Temperature (IAT)		approx. ambient air temperature

If the specified value is not obtained:

-- Continue the test according to the following table:

Indicated	Cause	Test
approx. -40° C or approx. -46° C	Open circuit or short circuit to (B+)	TESTING IF DISPLAY APPROX. -40 °C OR APPROX. -46 C OR APPROX. -46 °C:
approx. 140° C	Short circuit to Ground (GND)	TESTING IF DISPLAY APPROX. 140 °C:

If the specified values are obtained:

-- Remove the Intake Air Temperature (IAT) Sensor -G42-. Refer to Repair information.

-- Spray the Intake Air Temperature (IAT) Sensor 2 -G299- with a commercially available cool spray while observing the temperature value on the scan tool.

The temperature value must decrease.

-- End diagnosis and switch the ignition off.

If the intake air temperature does not decrease:

-- Replace the Intake Air Temperature (IAT) Sensor 2 -G299-. Refer to Repair information.

If the intake air temperature does decrease:

Checking internal resistance 

-- Disconnect the Intake Air Temperature (IAT) Sensor 2 -G299- electrical harness connector -arrow-.

-- Using a Multimeter, check the Intake Air Temperature (IAT) Sensor 2 -G299- terminals 1 to 2 for resistance.

Use the chart below for the specified values:

• Area A: Resistance values 0 to 50 °C.
• Area B: Resistance values 50 to 100 °C.

Specified values:

Read-out examples:

• Range A, 30° C equals a resistance of 1.5 to 2.0 kΩ
• Range B, 80° C equals a resistance of 275 to 375Ω

If any of the specified values are not obtained:

-- Replace the Intake Air Temperature (IAT) Sensor 2 -G299-. Refer to Repair information.