P0746 Fault Code in BMW: Causes, Symptoms, and Fixes

The Transmission Control Module (TCM)** has detected that the pressure control solenoid “A” is not regulating hydraulic pressure properly — it may be stuck, not responding, or working outside expected parameters.
This solenoid controls fluid pressure inside the valve body, which affects gear changes and clutch engagement.

Symptoms:

1. Check Engine Light (CEL)
2. Harsh or delayed shifting
3. Slipping between gears
4. Car stuck in a single gear or limp mode
5. Transmission overheating
6. Poor acceleration or jerky movement

Common Causes:

1. Stuck or faulty pressure control solenoid “A”
2. Dirty or low transmission fluid
3. Debris in valve body channels
4. Faulty wiring or bad connector to the solenoid
5. Failed TCM (Transmission Control Module)
6. Internal hydraulic leaks

Fixes:

✅ Step-by-Step:
1. Scan the transmission module
– Use a scan tool like ISTA+ (for BMW), VCDS (for Audi/VW), or a generic OBD-II with live data
– Check other related codes (P0741, P0700, etc.)
2. Check transmission fluid
– Level and condition (should be clean and red, not dark or burnt)
– Change fluid and filter if dirty or overdue
3. Inspect wiring and connectors
– Check for corrosion, pin damage, or loose connections at solenoid or TCM
4. Test or replace the pressure control solenoid “A”
– Located inside the valve body (or mechatronics unit in DSG/DCT gearboxes)
– Requires transmission pan removal in most vehicles
5. Flush or clean valve body
– If solenoid is functioning but valves are sticking due to debris
6. Reprogram or update TCM (if applicable)
– Especially in newer BMW, Audi, and Nissan models

Vehicles Commonly Affected:

1. BMW (ZF 6HP / 8HP, GM 6L50)
2. Audi/Volkswagen (Tiptronic, DSG)
3. Nissan (RE0F10A CVT)
4. Toyota (Aisin automatic transmissions)
5. Mercedes-Benz (722.6 / 722.9)
6. Honda (5-speed ATs)