P2B4BB Camshaft Position Actuator Position Sensor B Circuit 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
- P2B4B is set when the circuit feeding the second position sensor (B) of the exhaust actuator on bank 2 is open or otherwise unusable. Bank 2 exists only on engines with two cylinder rows, such as the Mercedes M176/M177 V8, whose CAMTRONIC bulletin lists exhaust feedback faults on bank 2 for sensor A (P34C1, P34C2) but not for sensor B. No manufacturer has published a description of P2B4B, so the diagnosis follows the general pattern: check plug, wires and sensor supply, then the sensor in the actuator. Mercedes also found heat damage on the harness above the bulkhead on these engines. CARB expects electronic parts of valve-lift systems to be monitored for circuit faults. Bank 1 exhaust counterpart: P2B47.
- What you may notice
- Check engine light on
- Cylinder deactivation or exhaust lift change unavailable
- Somewhat higher consumption
- Likely causes
- LikelyPlug or wires at the actuator open
- PossibleHeat damage to the harness above the bulkhead
- PossibleSensor in the exhaust actuator failed
- 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 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.