P26C2Engine Coolant Bypass Valve D Stuck Closed
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P26C2 is the closed-side partner of P26C0, and GM again applies it to the block rotary valve of its engines. The test is the same comparison of commanded and actual angle, at least 10° apart in the 2019 L3B table (Type A, one trip) and 5° in the 2025 table 25OBDG03B (Type B), but here the raw feedback stays below 50°, so the valve is judged closed. The diagnostic is skipped while the end stops are being learned and when system voltage is under 11 V. GM bulletin 21-NA-149 includes P26C2 in its list of codes from a chafed engine harness. A block valve that stays shut stops coolant from circulating through the block, so local hot spots and engine overheating are the real risk; reduced power or a warning may follow.
- What you may notice
- Check engine light, immediately on GM 2019 L3B
- Rising coolant temperature or overheat warning
- Reduced engine power
- Likely causes
- LikelyBlock valve seized on the closed side
- PossibleChafed engine harness (GM bulletin 21-NA-149)
- RareWeak actuator motor unable to open the valve
- 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.