P0702 Fault Code in Audi: Causes, Symptoms, and Fixes

P0702** is a generic OBD-II fault code that indicates a general electrical malfunction in the transmission control system.
This code is triggered when the ECU detects an electrical fault (voltage, resistance, or short) in the TCM (Transmission Control Module) or related components.

Common Symptoms:

1. Check Engine Light (CEL)
2. Transmission stuck in limp mode (usually 2nd or 3rd gear)
3. Delayed or harsh shifting
4. Vehicle may not shift at all
5. Unresponsive gear selector
6. ABS or ESP light may also turn on in some cars

Common Causes:

1. Short circuit or open circuit in transmission wiring
2. Faulty TCM (Transmission Control Module)
3. Blown fuse or relay controlling the TCM
4. Grounding issue (loose or corroded ground connection)
5. Damaged connector on valve body or solenoids
6. In rare cases: bad ECU or CAN bus communication fault

Fixes and Diagnosis Steps:

✅ Step-by-step:
1. Scan with a full-system OBD2 tool (not just engine module)
Check for additional TCM codes like P0746, P0715, P0722, etc.
2. Inspect transmission wiring harness
Look for burnt, corroded, pinched, or water-damaged wires
3. Check fuses and relays
Look up the fuse box layout and test the TCM fuses using a multimeter
4. Check TCM connector
Ensure it’s seated properly and pins are clean
5. Measure voltage at TCM
Should be 12V supply and solid ground
6. Clear the code and test drive

Applies To:

1. Audi, BMW, VW, Mercedes-Benz, Toyota, Ford, etc.
2. Common with DSG, Tiptronic, 6HP/8HP, and CVT transmissions