7 Bad Car Thermostat Symptoms You Shouldn’t Ignore

1. Engine Temperature Fluctuates

Your engine should stay at a steady temperature once it warms up. If the temperature gauge on your dashboard jumps up and down while you’re driving, it might mean your thermostat isn’t working properly. A faulty thermostat may open and close at the wrong times, causing your engine to be too hot or too cold. If this happens, it’s time to consult a trusted Auto Repair expert who can inspect the issue.

2. Car Overheats

One of the most obvious signs of a bad thermostat is an engine that overheats. The thermostat’s job is to allow coolant to flow when your engine becomes hot. If it gets stuck closed, the coolant can’t do its job, and the engine gets hotter and hotter. Overheating can damage your engine and lead to costly repairs. This is something Wright's Car Care often sees when drivers wait too long to get things checked out.

3. Heater Doesn’t Work Right

When it’s cold outside, your car’s heater should keep you warm. However, if your thermostat is stuck open, your engine may never reach a sufficiently high temperature to warm the air inside the vehicle. This means your heater blows cold or lukewarm air. If your cabin isn’t heating up like it used to, it could be more than just a broken heater. It might be your thermostat, and that’s something a local Auto Repair technician can diagnose.

4. Coolant Leaks

Thermostat problems can cause coolant to leak. When the thermostat fails to open, the pressure inside the cooling system increases. This can lead to leaks from the radiator, hoses, or the thermostat housing itself. If you see colorful fluid (usually green, yellow, or pink) under your car, don’t ignore it. Wright's Car Care warns that driving with low coolant can exacerbate the issue and even cause the engine to fail.

5. Strange Noises

Sometimes, a faulty thermostat can cause your car to sound different. You might hear gurgling or knocking noises coming from the engine area. These sounds often indicate that air is trapped in the cooling system or that the coolant is boiling. These are not normal noises and should be checked out at an Auto Repair Shop before they lead to bigger issues.

6. Bad Gas Mileage

A thermostat that stays stuck open means your engine stays too cold. When your engine is cold, it burns more fuel than usual. This can lower your gas mileage and increase your costs at the pump. Many drivers don’t connect fuel problems with a thermostat, but Wright's Car Care points out that poor fuel economy is often a hidden sign of this issue. If your gas tank isn’t lasting as long as it used to, the thermostat might be to blame.

7. Check Engine Light Comes On

That little orange light on your dashboard—yes, the one that says “Check Engine”—can light up for many reasons. One of them is a faulty thermostat. Today’s cars have sensors that watch engine temperature. If something isn’t right, the computer will send a signal to turn on the light. While the light doesn’t say “thermostat,” a skilled auto repair technician can use a scanner to identify the actual problem. Often, they’ll find that the thermostat is either stuck or not reading correctly.

Don’t Wait – Take Action Now

Your car’s thermostat may be small, but ignoring its problems can lead to big repairs down the road. From overheating and coolant leaks to poor gas mileage and failed heating, a bad thermostat causes more than just a little inconvenience. It affects your comfort, your wallet, and your car’s life.

If you’ve noticed any of these signs, don’t wait. Visit a professional Auto Repair Shop where trained mechanics can inspect your thermostat and cooling system. Wright's Car Care has helped countless drivers identify and resolve thermostat problems before they escalate into major engine issues. Whether your car runs too hot, your heater won’t work, or your coolant keeps leaking, the team at Wright's Car Care can get you safely back on the road.