P2E81Cold Start Engine Coolant Bypass Valve D Stuck Closed
- 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
- P2E81 is the cold-start version of P26C2 for valve D, which GM uses as the block rotary valve between two mechanical end stops. Its 2025 ECM tables (25OBDG03B) count a failure when commanded and measured position differ by more than 5° while raw feedback stays below 50°, i.e. on the closed side, in 4 of 5 seconds; Type B, MIL after two trips. It only runs in low-flow coolant mode (also with auto-stop) and with catalyst warm-up active, at 11 V or more, with block coolant above −34 °C and no calibration run for 37 s. CARB asks that faults found during the cold-start strategy carry their own codes. Keeping coolant still in the block is intended at first, as a Ford patent explains, but a valve that will not open later risks hot spots. The open side is P2DE8.
- What you may notice
- Check engine light after two trips
- Engine temperature rising faster or unevenly after a cold start
- Usually no driveability change
- Likely causes
- LikelyBlock rotary valve stuck on the closed side (deposits, wear)
- PossibleValve actuator too weak to turn the valve when coolant is cold and thick
- PossibleChafed or corroded harness to the valve actuator
- RareInvalid end-stop learn values after repair or battery disconnect
- 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 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.