P2681Engine Coolant Bypass Valve A Control Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- Bypass valve A is an electrically driven coolant valve whose role differs by maker. P2681 flags an open or otherwise faulty drive circuit. GM's 2011 Volt table checks it in the HPC2/VICM: 40 failures in 50 samples at 100 ms, Type B. Ford's 2020–2023 gasoline summary defines valve A as the automatic transmission cooler flow (transmission warm-up) valve and sets the code when its smart driver reports a fault for 5 s. Toyota bulletin T-SB-0112-24 (A25A and M20A engines, 2018–2021) replaces the water valve for P2681 subtypes 11 (circuit grounded) and 15 (open circuit or battery short). Ram 1500 3.6 L trucks needed a new three-way coolant valve with a cracked gear (07-005-24); VW reflashed 2024 Atlas engine controllers.
- What you may notice
- Check engine light on
- Slow warm-up of engine or transmission
- Maintenance or temperature warning message
- Likely causes
- LikelyFailed bypass valve (motor, gear or electronics)
- PossibleChafed harness or open fuse in the valve supply
- PossibleLoose or corroded valve connector
- RareEngine control software causing false detection
- 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: €80 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.