P0712 Fault Code in Audi: Causes, Symptoms, and Fixes

The P0712 fault code indicates that the Transmission Control Module (TCM) is receiving a low voltage signal from the Transmission Fluid Temperature (TFT) Sensor “A” — typically meaning the sensor is reporting an abnormally low temperature (e.g., −40°C or lower), which is often incorrect.

Common Symptoms:

1. Check Engine Light (CEL)
2.️ Harsh or delayed gear shifting
3. Vehicle stuck in limp/safe mode
4. Transmission not shifting properly during warm-up
5. Torque converter lock-up failure
6. Poor performance in cold conditions

Common Causes:

1. Faulty TFT sensor (shorted internally)
2. Open circuit or short to ground in sensor wiring
3. Corroded or loose sensor connector
4. Very cold weather (rare, if actual temp is low)
5. Faulty TCM (rare)

How to Fix It:

✅ Step-by-step:
1. Read live sensor data
– If TFT shows something like −40°F (−40°C), the signal is likely shorted
2. Inspect and test sensor wiring
– Look for frayed wires, pinched harnesses, or corrosion at the connector
3. Test the TFT sensor
– Use a multimeter to measure resistance (should vary with temperature)
4. Replace the sensor if shorted or reading unrealistically low
5. Clear the code and test drive

Sensor Location:

1. Often located inside the transmission, on the valve body or part of the internal wiring harness
2. On DSG/dual-clutch transmissions, it may be part of the mechatronics unit

Affects:

Audi, VW, BMW, Toyota, Hyundai, Honda, Mercedes-Benz, Ford, etc.