P26ACEngine Coolant Bypass Valve B Control Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- Which valve carries the letter B depends on the maker. Ford names it in its gasoline OBD summaries for 2020–2023 and 2024–2025: valve B is the active transmission cooling valve, which sends engine coolant to the automatic transmission oil cooler, while valve A heats the transmission. P26AC is set when the smart driver in the PCM reports a fault on that output for 5 s; in 2024 Ford also files it under the extended code P26AC_13 for an open circuit. CARB lets makers combine open, low and high faults of an output into one code, which is why P26AC is often the only electrical code used. With the valve unpowered, transmission oil may run hotter or colder than intended.
- What you may notice
- Check engine light
- Transmission fluid temperature higher than normal when towing
- Usually no change in normal driving
- Likely causes
- LikelyBroken wire or unplugged connector at valve B
- PossibleOpen solenoid or motor winding in the valve
- RareFaulty output driver in the PCM
- 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.