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Summary
  • The engine coolant over-temperature light warns about an overheating engine.
  • Common reasons for an engine coolant over-temperature alert include coolant leaks, faulty cooling parts like fans or water pumps, and internal issues with the engine.
  • It’s unsafe to keep driving with an illuminated temperature light.
  • Overheating can lead to blown head gaskets, blown radiators, and fractures in the cylinder heads or engine blocks.

The engine over-temperature light is the most concerning warning that can pop up on your car’s dashboard. Allowing your vehicle to overheat even once can have dire consequences, including costly internal engine damage.

You should never ignore the engine temperature warning light. If the light illuminates on your dashboard, you’ll want to pull over and shut off the engine immediately.

temperature warning light
If the engine temperature warning light illuminates on your dashboard, it means your car’s engine is overheating.

What Does the Engine Coolant Over-temperature Alert Mean?

Not all vehicles have an engine temperature warning light (some cars only have a temperature gauge). But for those that do have a light, exactly what the warning looks like will vary by vehicle.

Some cars may warn of an engine over-temperature condition by displaying a string of text in the driver’s information center. Others will turn on an illuminated symbol depicting a thermometer floating in coolant.

Regardless of the warning’s appearance, the message is always the same: Your car’s engine is overheating.

What Should the Engine Coolant Temp Be?

Most modern engines have a normal coolant temperature operating range between 195 and 225 degrees Farenheight. Anything hotter than the peak normal operating temperature is considered to be overheating.

Why is My Coolant Overheating?

Contrary to what Hollywood movies might lead you to believe, cars don’t spontaneously overheat for no reason. In reality, engines overheat when there’s something wrong—and there are many possibilities for what that something might be.

To determine the cause of the overheating condition, you (or your mechanic) will need to do some diagnostic work.

woman checking overheating car engine
Engines overheat when there’s something wrong—and there are many possibilities for what that something might be.

Common Causes for Engine Overheating

If your car is overheating, there’s a good chance you’ll find one or more of the following problems to be the cause:

Leaks Leading to a Low Coolant Level

Your car’s cooling system is an assortment of components and hoses, nearly all of which can develop leaks. Leaks often lead to a low coolant level, resulting in engine overheating.

Failed Thermostat

The thermostat is one of the most important parts of the cooling system. When the engine is below normal operating temperature, the thermostat is closed to prevent coolant from circulating from the engine to the radiator. Keeping the thermostat closed under these conditions allows the engine to warm up more quickly for improved efficiency and performance.

When the engine reaches operating temperature (usually around 195 degrees), the thermostat opens, allowing coolant to flow from the engine to the radiator, then back again. The radiator transfers some of the heat from the coolant to the atmosphere to effectively remove heat from the engine.

Like any automotive part, the thermostat can eventually fail. If it fails in the closed position, coolant will not be able to circulate between the engine and the radiator, resulting in the engine overheating.

Faulty Water Pump

Your car’s water pump contains a multi-blade impeller that forces coolant to circulate throughout the cooling system. Most water pumps are driven off of the engine by a drive belt, timing belt, or timing chain.

If the water pump or its drive mechanism fail, coolant will no longer flow properly through the cooling system and the engine will overheat.

broken water pump
If the water pump is broken, the coolant will no longer flow properly through the cooling system and the engine will overheat.

Damaged or Obstructed Radiator

The radiator is a heat exchanger that dissipates heat from the hot engine coolant into the atmosphere. When the vehicle is moving down the road, air flows through the front grille and the radiator to remove heat. In situations where the vehicle is idling or moving slowly, one or more fans move air through the radiator.

Over time, the radiator may become damaged or obstructed, leading to engine overheating.

Inoperative Cooling Fan

As is noted above, the radiator relies on a cooling fan to provide airflow when the vehicle is idling or traveling slowly. If that fan isn’t working properly, either due to an internal failure or a circuit problem, the engine will overheat.

Internal Engine Problem

There are a few common internal engine problems—including blown head gaskets, cracked cylinder heads, and cracked engine blocks—that can lead to internal coolant leaks and overheating.

Depending on where the leak is located, the coolant may either enter the engine’s combustion chamber (and get burned) or the lubrication system (and mix with engine oil). Either scenario can lead to a low coolant level and engine overheating.

It’s also important to note that blown head gaskets, cracked cylinder heads, and cracked engine blocks often result from engine overheating, as we’ll discuss below.

broken car engine due to overheating
Some of the most common consequences of overheating include blown radiators, blown head gaskets, cracked cylinder heads, and cracked blocks.

Is It Safe to Drive With an Activated Temperature Light on the Dash?

No, it’s dangerous to drive while the engine temperature warning light is on. If you continue driving, you’d risk damaging your engine, which could lead to costly repairs.

So take your ride to an auto repair shop when you notice the warning light is on, especially if you spot signs of engine overheating.

Find a safe spot to park, but don’t inspect the hood immediately. The extreme heat when you lift the hood could injure you. Instead, contact a towing service to take your ride to an auto repair shop.

Why Does My Engine Temperature Light Go On and Off?

If it flashes and disappears when you start your vehicle, you have nothing to worry about. This process is called bulb check, and it’s meant to ensure the bulbs on your dash warning lights are functioning as they should.

Start worrying if the light is still on after driving for a few minutes. If your car isn’t overheating, you might be dealing with a faulty coolant temperature sensor.

What Happens if Coolant Gets Too Hot?

Big-time problems can result from engine overheating. Some of the most common consequences of overheating include blown radiators, blown head gaskets, cracked cylinder heads, and cracked blocks.

But there are other major (and costly) problems that can result from overheating, as well. Extreme heat can cause various internal engine components to expand, leading to problems, such as damaged valves and scuffed pistons.

High operating temperatures can also lead to detonation, which can destroy internal engine components.

How Do You Fix Coolant Over Temperature?

If your car’s engine overheating light comes on, you should pull over and shut off the engine immediately. Then, have the car towed to your destination of choice for repair.

Once you have the vehicle in a safe place, you (or your mechanic) will need to diagnose and repair the underlying cause of the overheating concern. Do not drive the car until the problem is fixed.

Replacing Parts Damaged by an Overheating Engine

When the engine overheats, it can cause various problems, from blown head gaskets and radiators to engine block damage. Driving while such crucial components are faulty or damaged isn’t a good idea. If your mechanic recommends replacing a part, consider shopping online at CarParts.com for a top-notch replacement.

With only a few clicks, you can find the right part for your ride on our website. After entering your car’s specifications into our vehicle selector, use the search filters to narrow down the options to the ones that match your preferred brand, price, and features.

Because our parts come with a low-price guarantee, you don’t need to break the bank to get an OE-grade replacement. All our products are on hand and ready to ship, so you don’t have to wait long for your new part.

Make sure your engine and its surrounding parts are in tip-top shape. Shop for replacement parts here at CarParts.com today!

About The Author
Written By Automotive Subject Matter Expert at CarParts.com

Mia Bevacqua has over 14 years of experience in the auto industry and holds a bachelor’s degree in Advanced Automotive Systems. Certifications include ASE Master Automobile Technician, Master Medium/Heavy Truck Technician, L1, L2, L3, and L4 Advanced Level Specialist. Mia loves fixer-upper oddballs, like her 1987 Cavalier Z-24 and 1998 Astro Van AWD.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

File Under : DIY , Warning Lights
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anatoli

Very informative! Thanks a lot!

Hello,

Thank you for the positive feedback! We’re glad you found this article to be helpful.

Nitta

Thanks so much for this article. Tonight while at McDonald’s drive thru this temperature light came on. As a woman I had no clue what it meant so I googled and this article popped up and told me to turn the car of and let it cool down. I did so immediately. Once I got home and was able to read the full article, I became well informed of what I was dealing with. Now I know not to drive anywhere if I don’t have to and to get my car to a mechanic ASAP! Thank you so much for educating those of us who don’t have a clue and saving us a great deal of money.
God bless you.

Sam

I have a 2015 Fiat 500, dash gauge indicates engine temperature is normal, however a warning pops up randomly saying engine coolant temperature high turn engine off… ideas?

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