P0708 Fault Code in Audi: Causes, Symptoms, and Fixes

P0708** is a diagnostic trouble code (DTC) that indicates the Transmission Control Module (TCM) or Engine Control Module (ECM) has detected a high input voltage from the Transmission Range Sensor (TRS) – also called the Neutral Safety Switch.
This typically means the sensor is sending an abnormal or out-of-range signal, which confuses the system about what gear the vehicle is in (P, R, N, D, etc.).

Common Symptoms:

1.️ Check Engine Light (CEL)
2. Vehicle won’t start in Park or Neutral
3.️ Transmission stuck in limp mode
4. Reverse lights may not work
5. Gear position not displaying properly
6. Cruise control may not work
7. Harsh or delayed shifting

Common Causes:

1. Faulty transmission range sensor (TRS)
2. Short to power or open ground in TRS wiring
3. Corroded, loose, or damaged connector
4. TRS misalignment after service or installation
5. Water or moisture in the sensor plug
6. Faulty TCM or ECM (rare)

How to Fix It:

✅ Step-by-step:
1. Scan all transmission-related codes
– Use a full-featured scan tool (e.g. Launch, Autel, VCDS)
2. Inspect the TRS and its connector
– Look for signs of water ingress, corrosion, or loose pins
3. Check wiring for shorts or fraying
– Focus on wires from TRS to TCM
4. Test the TRS with a multimeter
– Compare voltages across different gear positions
5. Replace the transmission range sensor if faulty
– On most vehicles, it’s mounted to the side of the transmission
6. Clear the code and test drive

Applies To:

1. VW / Audi DSG (DQ200, DQ250)
2. BMW ZF transmissions
3. Hyundai / Kia, Ford, Toyota, Mercedes-Benz, and more