P2B86Coolant Pump A Overspeed/Air in System
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2B86 says coolant pump A spins faster than it was told to – the typical sign of air at the impeller. In GM's 2025 tables (25OBDG03A, 25OBDG04B) the filtered gap between command and feedback must stay beyond a map limit, the pump running 200 to 348 rpm too fast depending on the 300–3,480 rpm request, over 8 s of a 10 s span at more than 11 V; Type B. On GM trucks pump A is the G17 auxiliary heater pump: bulletin PIT6505 (2024–2026 Escalade, Tahoe, Suburban, Yukon) found a stray O-ring lodged in it. Ford's 2024 gasoline summary has P2B86 as overspeed/dry-run type of the cabin-heating pump. Bentley sees P2B8600 with P2B6500 on W12 models (bulletin 2066669) and checks the bleed hose. Too slow: P2B87.
- What you may notice
- Check engine light after the second faulty trip
- Weak or fluctuating cabin heat
- Coolant warning or gurgling noise in the heater area
- Likely causes
- LikelyAir trapped in the loop after a repair or incomplete bleeding
- PossibleCoolant loss through a leak, low level in the reservoir
- RareForeign object such as a loose O-ring at the pump ports
- RareRestricted bleed or vent hose keeping air in the system
- 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: €60 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.