P2B5DEngine Coolant Flow Control Valve Position Sensor Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2B5D is the general circuit code for the position sensor of the coolant flow control valve, the feedback that tells the engine computer how far the rotary valve has turned. No manufacturer documents this exact code publicly. GM's 3.0-litre Duramax, whose valve reports its position digitally over a SENT link, covers the sensor through the low and high codes P2B5E and P2B5F and a separate communication check instead. A system using P2B5D would flag an implausible or missing signal that fits neither low nor high. CARB 13 CCR 1968.2 (e)(15) requires such input circuits to be checked for continuity. With no valid position the engine computer cannot regulate coolant flow and usually parks the valve in a safe position.
- What you may notice
- Check engine light on
- Coolant flow control in fallback, warm-up or heating behaviour changed
- Likely causes
- LikelyLoose or corroded terminals at the valve connector
- PossibleSignal, reference or ground wire of the sensor interrupted
- RarePosition sensor inside the valve faulty
- 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: €50 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.