P26BFEngine Coolant Bypass Valve D Control Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P26BF stands for battery voltage on the valve D control line where the driver expects a switched or grounded level. Ford documents it in its 2024–2025 gasoline OBD summary: the cabin heating bypass valve is valve D, and a short to battery reported by the PCM's smart driver is stored as P26BF, internally also as P26BD_12, after continuous monitoring for 5 s. The 2020–2023 summary still listed only P26BD for this valve, so older Fords report the same fault under the general code. GM's public tables do not use P26BF. A short to positive can keep a low-side switched valve permanently on or trip the driver protection. Since this valve controls heater flow, expect heat that cannot be turned down or does not come at all.
- What you may notice
- Check engine light
- Heater stays hot or stays cold regardless of setting
- Likely causes
- LikelyControl wire shorted to battery voltage
- PossibleHarness damaged near hot or moving engine parts
- RareInternal fault in valve D
- 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 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.