P26A8Engine Coolant Bypass Valve A Position Sensor Circuit Intermittent/Erratic
- 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
- P26A8 targets a feedback signal that jumps or drops out briefly instead of staying wrong. No manufacturer publishes a definition for this exact code. The closest documented logic is in GM's 2011 Volt table, where under P26A9 the controller flags a reading that changes by more than 6 % between samples ten steps apart (8 of 10 or 80 of 100 samples) although no movement was commanded. Subaru's bulletin 09-80-21 lists P26A-series codes as consequences of moisture reaching the sensor of the thermo control valve on 2019–2021 models. CARB asks for rationality checks on inputs that affect emissions. In practice a loose terminal, a cracked solder joint or a worn sensor track causes it, often only with vibration or heat.
- What you may notice
- Check engine light that may come and go
- Erratic heater output or engine temperature
- Code returns after clearing, often on rough roads
- Likely causes
- LikelyLoose or spread terminal in the valve connector
- PossibleWorn or contaminated sensor track giving dropouts
- PossibleHarness rubbing on engine parts and shorting intermittently
- 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: €60 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.