P2B56B Camshaft Profile Actuator B Control Stuck On Bank 2
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2B56 completes the series: on bank 2 the second actuator of the exhaust camshaft remains engaged after it should have released. No manufacturer publishes a description of this exact code. NTN-SNR lists it as permanently active; CARB 13 CCR 1968.2 (e)(13) is the legal basis for monitoring such valve control functions. Mercedes uses the stuck-off counterparts on the exhaust side of its M176/M177 V8 (P005A/P005C), which shows that V8 sliding-cam systems monitor each bank separately. Typical reasons are a sticking solenoid, a worn shift groove or low oil quality that hinders the pin. One bank then keeps the wrong exhaust lift. Bank 1 equivalent: P2B55; stuck off: P2B52.
- What you may notice
- Check engine light on
- Bank-to-bank imbalance felt as rough idle or part-load vibration
- Lift switching locked by the engine control
- Likely causes
- LikelySolenoid of exhaust actuator B on bank 2 sticking in the engaged state
- PossibleAged or wrong engine oil slowing the pin
- RareWorn shift groove on the exhaust cam sleeve
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.