Thermo Control Valve Failure
ModerateCooling SystemLater Mk5 cars can suffer thermo control valve faults, bringing up dashboard warning lights and poor heater performance without an obvious external coolant leak. Lamps and electrical faults are the most common MOT failure area on the Impreza.
Engine warning light, Cabin heater stays lukewarm, Cooling fans running oddly
- Check heater performance from cold
- Ask whether the valve has already been replaced
- Scan the car for stored cooling-related fault codes