P0E77Coolant Bypass Valve A Control Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P0E77 is logged when valve A's drive line carries more voltage than the driver should allow, typically because the wire has rubbed through against a 12 V feed. A low-side driver then sees battery voltage while it is trying to pull the line down and usually reports overcurrent; with some designs an open line can float high and end up here too. In either case the valve no longer follows commands reliably. No manufacturer documents P0E77 publicly. Ford's 2019 hybrid summary handles the same situation on its bypass valve as P2683, again set after more than 5 seconds of driver fault status. CARB expects such outputs to be checked for circuit faults. A grounded line is P0E76 and an interrupted one P0E75; replacing the valve without checking the harness first rarely helps.
- What you may notice
- Check engine light
- Cabin heat unstable or missing
- Likely causes
- LikelyControl wire shorted to a battery or ignition feed
- PossibleOpen circuit that the driver interprets as high
- RareFaulty valve A actuator electronics
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €60 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.