Can I drive with a bad thermostat? The short answer to this question is technically yes, but the long and smart answer is no. Yes, your car will still run but not very well. Without that thermostat properly working, it decreases performance and can cause damage. Most think a car would immediately overheat without a functioning thermostat and that may be true, but the car may also never warm up to its optimal temperature. Driving with a bad thermostat is a disaster waiting to happen. The thermostat serves an important role in your vehicle, it is basically a valve between the engine and radiator. When the coolant gets hot the thermostat opens letting the coolant pass to the radiator, if it is not hot then the thermostat stays closed allowing the coolant to circulate. Some common signs of a bad thermostat include your engine overheating or a fluctuation of your temperature gauge. If either happens get your vehicle into a certified shop as soon as possible. Overheating your vehicle is ex