P2B6CCoolant Pump D Overspeed/Air in System
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2B6C means coolant pump D is spinning faster than its command would explain, the signature of an impeller moving air instead of liquid. No manufacturer documents this exact code publicly. For pump B, Bentley stores the counterpart P2B6500 on W12 models and traces it to a restricting vent hose, and Ford lists P2B65 as failure type B1 (overspeed/dry run). Patent EP2743509A1 describes how dry running and air bubbles in an electric coolant pump can be recognised from the way its speed rises and decays after a defined energy input. Typical causes are a low level after a leak, incomplete bleeding after service and air pockets that gather at high points of the loop. Bleed the circuit with the manufacturer's routine and look for leaks. A stalled pump D is P2B6A.
- What you may notice
- Coolant warning or rising temperature display
- Gurgling from the cooling circuit
- Coolant level drops in the expansion tank
- Likely causes
- LikelyCircuit not fully bled after filling or repair
- LikelyCoolant lost through a leak
- PossibleVent line or bleed valve restricted, air cannot escape
- 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 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.