A Quick Guide on the Engine Temperature Warning Light

Written by

CarParts.com Research Team

Automotive and Tech Writers

Updated on November 26th, 2024

Reading Time: 4 minutes
Summary
  • The engine temperature warning light indicates that the engine is running dangerously hot.
  • The warning light turns on because of an overheating engine, low engine coolant level, and engine cooling system problems.
  • If the engine temperature warning light turns on, pull over into the shade, let the engine cool down and rest, check its temperature and coolant level, and replenish the coolant.

Driving with an overheated engine is a surefire way of damaging the mechanism. Fortunately, the engine temperature warning light will warn you about the problem. Let’s take a look at what this warning light entails when it illuminates, what conditions trigger it, and what you should do when you notice it’s on.

What the Engine Temperature Warning Light Means

The engine temperature warning light indicates that the engine is running dangerously hot. If you see this light turned on, stop whatever you’re doing and find a safe way to cool the engine.

You can find the engine temperature warning light on the dashboard gauge cluster. It resembles a thermometer for easier recognition. It might also have a label saying “temp” or the phrase “engine overheating.”

When you start your vehicle, warning lights will turn on as they test their light bulbs for possible issues. One of these self-testing lights is the engine temperature warning light. Thus, there’s no need for concern if you see this warning light glow during the first few seconds after the engine starts. However, if the engine temperature warning light keeps glowing, it’s important to react correctly.

What Triggers the Engine Temperature Warning Light?

So, what prompts the PCM to activate the engine temperature warning light? Here are the three primary issues that trigger this light:

Overheating Engine

If the engine overheats, the engine temperature warning light turns on. It’s as simple as that.

Your vehicle’s powertrain control module (PCM) monitors various factors that affect how the engine runs, such as the temperature of the engine coolant. The computer uses the readings provided by the engine coolant temperature sensor, which measures how hot the coolant is.

If the sensor readings show that the coolant is much hotter, the PCM will activate the engine temperature warning light.

Low Engine Coolant Level

In many cases, the engine overheats because it’s short on coolant. Fortunately, you can fix this problem by filling the coolant reservoir with new engine coolant.

Engine Cooling System Issues

The engine cooling system has many parts that work together. If one of its parts develops an issue or fails, the system cannot cool the engine as efficiently as it should.

Take the radiator fan for example. The fan blows air over the radiator. The airflow carries away the heat released by the heat exchanger, helping to cool the coolant passing through the radiator pipes. If the radiator fan operates erratically or stops working, it cannot cool the radiator.

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What Should You Do If the Engine Temperature Warning Light Turns On?

Is the engine temperature warning light illuminated? Here are the things you must do immediately:

Pull Over

It’s dangerous to drive with an illuminated engine temperature warning light that warns you about an overheating engine. Pull over on the side of the road as soon as it’s safe to do so.

Get In The Shade

If you’re driving during a hot day and the engine temperature warning light turns on, get out from under direct sunlight. Sunlight heats anything it shines upon.

Look for a shady area. The overhead shade will protect your vehicle and you from direct sunlight.

Let The Engine Cool Down

Give the engine a minimum of 30 minutes to cool down. Don’t shut down your vehicle immediately. Otherwise, you might cause heat congestion that makes the water even hotter.

Check the Temperature

Carefully apply water to the surface of the engine block. If the water boils, the engine remains too hot to safely turn off. Instead, let your vehicle idle until it cools off. Afterward, you can turn it off.

Check Coolant Level

You should wait for the engine to cool down before checking its coolant level. A hot engine might release steam that can hurt you.

Wear protective gear beforehand. Put on a thick glove or wrap a thick piece of cloth around your hands to protect them from the heat of the radiator and its contents.

Slowly unscrew the coolant reservoir cap to release the excess pressure safely. Leave the coolant reservoir open to let out heat while you check its contents.

Replenish Engine Coolant

You can usually fix a low coolant level by adding clean water to the coolant reservoir. It’ll mix with the remaining coolant and restore the cooling system’s performance.

Check For Coolant Leaks

However, refilling the coolant reservoir might only be a temporary fix if its coolant level drops because of a leak. You must find the source of the coolant leak and patch it up.

Let Your Vehicle Rest

Do you work your vehicle hard? Is it heavy to begin with, overloaded, or both? Its engine can run excessively hot from propelling the overloaded car.

Your vehicle needs breaks. Once its engine has cooled down, you can operate it again.

Use the OBD-II Scan Tool

If your vehicle develops an issue, the PCM will usually set the relevant diagnostic trouble code. You can view the trouble codes by plugging an OBD-II scanner into the PCM. Look up the details of the trouble code to see if you can fix the problem.

What Happens When You Keep Driving with the Engine Temperature Warning Light On?

Driving with an illuminated engine temperature warning light can cause serious engine problems. The engine might even fail.

The heated metal expands in volume, increasing the chances of engine parts directly touching each other. The metal-to-metal contact produces more friction, abrades the surfaces of parts, and makes a knocking noise. It can damage critical parts like the camshaft, head gasket, O-ring, pistons, valves, and other engine parts.

Overheating will also inflict significant thermal stress on the cylinder head and engine block. Aluminum cylinder heads are more likely to fracture from the heat and pressure.

Always heed the engine temperature warning light. If it illuminates, immediately get your car to a safe spot. Identify the problem and see if you can fix it long enough to get to a trusted auto repair shop. Otherwise, call for a tow to prevent further damage to the engine.

Written By CarParts.com Research Team

Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

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.