The thermostat within your vehicle maintains the engine's temperature and ensures it's operating with a range that's specified in your vehicle's owner's manual. Thermostats serve two main functions, to heat the engine and keep it consistently at optimum temperature. As you drive, the thermostat gets older and worn. A worn thermostat can get stuck open or closed, leading to an array of problems. It may not be easy to determine whether the thermostat is the main problem culprit when issues occur. Below we provide a brief overview of signs to look out for that indicate the thermostat needs to be replaced.   There's cold air blowing through the heater vents. If the thermostat is stuck open, the temperature within the engine will decrease.  The engine is overheating. If the engine is smoking and overheating, the thermostat may be stuck closed. A thermostat that is stuck in the closed position wi ... read more