P26B4Fuel Shutoff Valve A Control Circuit Stuck On
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P26B4 is the opposite failure to P26B3: shut-off valve A stays open or energised when the module wants it closed. No manufacturer documents P26B4 in public sources. On the Roush propane system for Ford trucks, valve A is the tank solenoid (its open-circuit code is P0005), and GM's 2015 Impala Bi-Fuel uses two normally closed CNG cut-off valves that the ECM opens only in gas mode while the engine cranks or runs. A valve that cannot close defeats that safety function, so fuel may keep flowing into the lines after shut-off. Typical causes are a short to voltage on the control wire, a stuck driver or relay, or a mechanically jammed valve. CARB requires output monitoring. Have it fixed promptly; close the manual tank valve if fuel can be smelled.
- What you may notice
- Check engine light
- Fuel odour after shut-off
- Fuel pressure remains in the lines with the engine off
- Likely causes
- LikelyControl wire shorted to battery voltage
- PossibleSupply relay or driver stuck on
- PossibleValve A mechanically jammed open
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.