Ambient Air Temperature Sensor Checking

2012 Volkswagen Golf TDI, 2D Hatchback, Automatic DCT TransSECTION Ambient Air Temperature Sensor Checking

Special Tools And Workshop Equipment Required 

  • Multimeter.
  • Wiring diagram.

Test Procedure 

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

Start Diagnosis 

-- Connect the scan tool.

-- Engine MUST be at room temperature.

-- Turn the ignition switch ON.

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

Diagnostic text Specified value
Ambient Air Temperature (AAT) Sensor approx. ambient air temperature

-- Turn the ignition switch OFF.

If the specified value was obtained:

-- Fault may be intermittent. Check for proper connection, damaged wiring or loose terminals.

If the specified value was Not obtained:

Checking internal resistance

-- Disconnect the Ambient Air Temperature Sensor -G17- electrical harness connector.

-- Using a multimeter, check the Ambient Air Temperature Sensor -G17- terminals 1 to 2 for resistance.

Use the chart below for the specified values:

Specified Values: 

AAT Temperature vs Resistance
Temp (C) min. value ohms max. value ohms
- 40 31811 37560
- 35 22941 26863
- 25 12415 14289
- 15 6958 7880
- 5 4036 4495
0 3120 3442
5 2422 2655
15 1519 1623
25 968 1031
35 629 676
45 419 455
55 286 314
65 195 217
75 136 155

If The Specified Values Were Not Obtained: 

-- Replace the Ambient Air Temperature Sensor -G17-.

If the specified values are obtained, continue the test according to the following table:

Checking wiring

-- Turn the ignition switch ON.

-- Connect a multimeter to terminals 1 and 2 of the Ambient Air Temperature Sensor -G17- electrical harness connector.

Specified value: near 5 V

-- Turn the ignition switch OFF.

If the specified value was Not obtained:

-- Remove the Instrument Cluster.

-- Disconnect the Instrument Cluster harness.

-- Using a multimeter, check the Ambient Air Temperature Sensor -G17- electrical harness connector terminals 1 and 2 to the Instrument Cluster electrical harness connector for an open circuit or a short. Refer to Appropriate Wiring Diagrams for Pin locations.

Ambient Air Temperature Sensor -G17- electrical harness connector terminals Instrument Cluster -J285- electrical connector T32 terminals
1 27
2 19 or (Pin 20 for 2011)

Specified Value: 1.5 Ω Max. 

If the specified value was Not obtained:

-- Check the wiring for an open, high resistance or short circuit to Battery (+) or ground.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

If the specified value was obtained:

Replace the Instrument Cluster.

Final Procedures 

After the repair work, the following work steps must be performed in the following sequence:

  1. Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
  2. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
  3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.