P26BAEngine Coolant Bypass Valve C Stuck/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P26BA is meant for a valve C that stays open although the controller wants it shut, while its circuit tests fine. No manufacturer documents this code in public sources. GM and Ford, which both use the letter C, cover their valve C functionally through other codes: GM's L3B and diesel tables treat a valve that misses its target angle as P26BB, and Ford watches its radiator bypass only electrically. How an open-stuck check can be built is shown by GM's block valve logic for P26C0, which needs a position error of at least 10° while the feedback still reports the open side. CARB requires a functional test of output components where feasible. If the valve hangs open, coolant flows when it should not, so warm-up is slow and the engine may stay below its target temperature.
- What you may notice
- Check engine light
- Slow warm-up and lower temperature gauge reading
- Weak cabin heating in cold weather
- Likely causes
- LikelyValve C jammed in the open position by wear or deposits
- PossibleDirty or mixed coolant hindering valve movement
- RareIncorrectly learned end positions after a repair
- 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: €150 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.