شیر کنترل جریان مایع خنک‌کننده معیوب

The motorised valve that routes engine coolant on the module's command — the wax thermostat's electronic replacement. It fails as a motor, as a valve, or as the sensor between them: a winding or driver fault stops it moving, scale and debris bind the rotary element until the motor current gives it away, and a failed position sensor leaves the module driving a valve it cannot verify.

The direction of failure sets the urgency. Stuck toward open is a cold-running engine — inefficient, hard on emissions, safe. Stuck toward closed blocks coolant from the radiator and is an overheat in waiting; the temperature gauge outranks the code list the moment it climbs.