05 November 2024
Car Warning Lights Explained: Your Guide
6 minutes
A warning light on your car’s dashboard is never a welcome sight, especially if you’re not sure what it means. When you need car warning lights explained, it’s best to turn to your vehicle’s manual.
Across the different car makes and models available, there are well over 100 possible dashboard warning symbols, and most cars won’t use them all. But here, we’re breaking down the most common car warning lights so you know what to do when they appear.
What do the light symbols mean on a car?
Let’s look at the most common car warning lights that might appear when you turn on the ignition or as you’re driving.
As we describe the car dashboard symbols and meanings, we’ll look at what each light could be telling you. We’ll also point out the lights you should never ignore, and explain why you should pull over as soon as it's safe to do so whenever you see one switch on.
Note: Alongside the 15 symbols we cover here, your car probably has several lights connected to sensors that double-check, for example, that the doors are safely closed. This post will only cover the warning lights relating to the engine, brakes, and safety features of your car.
Airbag
A circle in front of a person in a seat.
The airbag warning light means that your airbag might not deploy. While this warning light won’t affect your car’s engine, it’s important to get it checked because the airbag could save your life in an accident.
Note: If you switch the airbag off yourself, for example, because you’ve had to put a rear-facing baby seat in the front passenger seat, the warning light will also illuminate.
Battery
A picture of a red, rectangular battery with negative and positive symbols.
If your battery light comes on, it’s usually because of a loose connection or because the battery is reaching the end of its life. It’s normal for a car’s battery to wear out after 3–5 years, and this dashboard warning light can tell you that you need to switch to a new battery very soon.
Brake system
A circle with an exclamation mark inside, surrounded by round brackets.
You should never ignore a brake warning light. Although it can sometimes mean that you drove away with the handbrake on (which is an easy fix), it’s there to warn you that your brakes might not perform as you need them to if you make a sudden stop.
Brake warning lights often come on if your brake pads are worn or your brake fluid is low. Both these problems make it unsafe to keep driving, so you should pull over and call your breakdown service as soon as it’s safe to do so.
Some cars may have more lights that tell you about the brakes. For example, the letters ABS are the anti-lock braking system warning light. If this light comes on alone, it tells you that the ABS isn’t doing its job and your car won’t perform as well as it should, but you still have brakes.
Check engine
A silhouette of an engine or the words ‘check engine’ on your onboard computer.
One of several yellow car warning lights on your dashboard, “check engine,” could mean many things. This light is connected to the motor and the car’s emissions system, so it covers a lot of ground. It could mean something as simple as a loose wire, but it could also be a much more serious problem.
If you’re driving when this light comes on, it’s important to stop as soon as you can. If it shows up when you start your car, postpone your journey until you get the engine checked. Your car might not be safe to drive, and you could make the problem much worse (and much more expensive to fix) if you ignore the light.
Coolant temperature
A thermometer over waves.
When your coolant temperature light comes on, it often means that the motor is too hot because of a broken pump, low coolant levels, or an issue with the radiator.
This is another warning light to pay close attention to. While you might still be able to drive while the car is overheating, you can cause a much bigger problem if you do.
Diesel Particulate Filter (DPF)
A picture of the exhaust with dots to indicate the soot.
When your DPF filter is blocked, it can’t stop the harmful soot from leaving your exhaust, which means that your car starts to produce black smoke. Your DPF is designed to self-clean when you travel at high speeds, but if you don’t regularly drive on main roads or over long distances, the filter might need to be cleaned manually.
It’s important to clean the filter or have it cleaned by a professional. First, the smoke your car produces when the filter is blocked lowers the air quality for everyone. Second, driving with a blocked filter can damage your engine.
Headlight
An illuminated bulb with an exclamation mark.
Your headlight warning symbol – which should look different from the symbols telling you that your lights are switched on – tells you that one of your bulbs has blown. You should check your lights as soon as you can and replace the bulb if necessary.
Driving without lights can cause an accident. The police also have the power to stop you and issue a fixed penalty notice for driving with a broken headlight.
Low fuel
A picture of a petrol pump (often with an arrow to show which side the cap is on).
Your fuel warning light will often come on when your tank is down to 10–15%. This light is easy to recognise and fix – just refuel your vehicle. When the light comes on, most cars can drive for 30–50 miles before the tank is empty, which should give you time to find a petrol station.
Oil pressure
A picture of an oil can with a single drop.
Like the check engine light, the oil warning light can be quite minor – for example, indicating that your car needs to be topped up with oil – or it could mean that you’re leaking oil. Because this light can indicate a serious problem like a broken oil pump or piston ring, it needs to be checked and fixed as soon as possible.
Power steering
A steering wheel with an exclamation mark.
Like the ABS warning light we mentioned above, the power steering light doesn’t mean you have no steering, but it can show that the enhanced system is broken. If you drive while the power steering light is on, but it’s important to be aware that the vehicle will be harder to manoeuvre.
Tyre pressure
An open circle with lines to represent tyre tread and an exclamation mark.
The tyre pressure light usually comes on when one tyre has less pressure than the others. It can mean that you need to inflate or replace that tyre.
You should try to deal with this warning light as quickly as possible, as you won’t be able to drive safely if your tyres are under or overinflated.
Traction control
A car with wavy lines to indicate skidding.
Traction control systems are designed to stop your car from slipping or skidding when you’re driving in poor conditions. If your vehicle has a traction control system, the light will probably come on while the system is in use. It tells you that your car lost grip, the system kicked in, and you should drive more cautiously.
In some cases, though, the warning light can also come on when the system is not functioning, in which case you should get it checked so you can benefit from all the safety features of the car.
Transmission temperature
A cog with a thermometer inside.
This warning light is connected to the car’s gearbox, and it can be a sign that the engine is working too hard and getting too hot. It often comes on if you’re towing a heavy load, if the transmission fluid is low, or if something in the engine is worn down and creating friction as it runs.
As with many of the other car dashboard warning lights on this list, you can cause serious damage to your engine if you keep driving while the transmission light is switched on.
Washer fluid
A windscreen with a jet of water.
While many drivers first notice that their washer fluid needs to be topped off when they try to wash their screen and nothing happens, some cars also have a warning light so you can top up before you run out completely.
What is the most serious warning light on a car?
There are certain warning lights that drivers dread seeing. After reading this list, you might well be asking, ‘What are the three most serious warning lights?’.
In summary, the engine and oil warning lights are rarely a good sign. They can indicate that something in your engine has seriously broken or is about to break, especially if they come on as you’re driving. When you see these lights, it’s important to stop moving as soon as it’s safe to do so because there’s a high chance you’ll make the problem worse if you keep driving.
It’s also important to pay attention to brake warning lights. If your brakes aren’t functioning correctly, your vehicle is a danger to yourself and others on the road.
Car dashboard symbols and meanings: Final word
Instrument panel warning lights can alert you to problems in many different areas of your car and its engine. Sometimes, they come on because of a bug in the system, and restarting your engine could be all it takes to make the light go away. Remember, modern cars have a lot of complex electrical systems, and sometimes a reboot is all it takes.
However, if the problem continues, it’s best to stop driving (in some cases immediately) and call in your breakdown assistance. They’ll often be able to plug a computer into your car’s onboard diagnostic systems and find out more about why the light has switched on. If there isn’t a problem, they’ll also know how to reset the warning lights on your car.
If you’re still wondering, “What do car warning lights mean?” Check your vehicle’s manual for a full explanation of the possibilities.
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