What Are the Symptoms of a Faulty Car Thermostat?

[KateLee]

After starting the engine, inspect by opening the filler cap of the coolant reservoir to see if there is any water flow inside. If there is no flow, it indicates that the thermostat is damaged or there is debris stuck between the main valve switches. The symptoms of a faulty thermostat are as follows: 1. Thermostat malfunction, where the opening is too small, affecting the engine's large and small circulation cycles, preventing effective heat dissipation, leading to increased engine temperature and the illumination of the coolant temperature warning light; 2. Thermostat opening too large, causing the engine temperature to be too low, slow temperature rise, increased fuel consumption, and abnormal engine noises; 3. Thermostat sticking, which can easily lead to carbon buildup, causing unstable engine idle and resulting in engine vibration.