Car dashboard warning lights

Car dashboard warning lights explained

Have you ever wondered what all those symbols that light up on your car’s dashboard mean? Our guide explains.

Graham King Cazoo

By Graham King

You’ve probably noticed that, when you turn your car on, its dashboard display lights up with lots of symbols. The lights normally then go out when the engine starts. You also might have seen some of the symbols light up while you’re driving.

Exactly what the symbols mean isn’t always clear, so it can be difficult to work out what they’re telling you. Here’s our guide to what car warning lights mean and what you should do about them.

What do dashboard warning lights mean?

When a warning light comes on, it’s indicating that the condition of your car has changed in a way that needs attention and may even affect your ability to continue driving safely.

The light takes the form of a symbol or a word that illustrates the problem. If your car has a digital driver’s display, you may also see a warning in text that gives some explanation of the problem.

There are some warning lights that every car has and others that relate to equipment that only some cars have. The symbols and words used are broadly the same across all cars, although manufacturers use different variations on the less common ones. We’ll cover the common warning lights – the ones you’re most likely to see – in more detail later.

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What causes warning lights to come on?

Not every light on your car’s dashboard is actually a warning light. You’re probably familiar with the green and blue symbols indicating that your car’s lights are on, and the yellow fog light symbols.

Most of the other lights on your car’s driver’s display indicate that there’s some sort of problem. Each one refers to a part of your car that’s developed a fault.

Some of them are fairly easy to resolve. The yellow petrol pump light, for instance, indicates that the car is running low on fuel. But other warning lights indicate more serious problems. Most of these refer to a low fluid level or to an electrical failure.

Many of the driver safety systems in the latest cars also show a warning light when they’re activated. Lane-departure warning and front-collision alert lights are among the ones you’re most likely to see. You’ll also see a light if one of the doors isn’t closed properly or if one of your passengers isn’t wearing a seatbelt.

Can I keep driving if a warning light comes on?

Every warning light requires you, as the driver, to take some sort of action. Depending on the problem, you might feel a change in how the car drives and possibly need to start looking for a safe place to stop. You should at least slow down to a safe speed, if necessary.

Many modern cars with a digital driver’s display show a message giving advice on what you should do when a warning light comes on. The severity of the problem is usually indicated by the colour of the warning light. A yellow light means there’s an issue that needs sorting out as soon as possible, but the car isn’t about to grind to a halt. Typical yellow lights include the low fuel light and the low tyre pressure warning. You should reduce your speed if necessary and start looking for a fuel station.

An amber or orange light means there’s a bigger problem. Again, the car isn’t about to grind to a halt but the engine may go into a low-power mode that makes the car move more slowly to prevent serious damage. Typical orange warnings include the engine management light and low oil level light.

A red light means there’s a serious problem that could affect your ability to drive safely. You should stop in the first safe place you can find, then call a breakdown service and have the car taken to a garage to be fixed. Typical red lights include the ABS (anti-lock brake system) failure warning and a triangular symbol that simply means ‘stop’.

Do I have to go to a garage when a warning light comes on?

You should always rectify any problems that occur with your car as soon as possible. There are some problems indicated by warning lights that you may be able to sort out yourself like refuelling, pumping up the tyres and refilling the oil.

If there’s a problem you can’t fix or even identify, you should take your car to a garage as soon as possible.

Are warning lights an MOT failure?

Ideally, you should fix any faults before it has an MOT test, whether or not there’s a warning light. If that’s not possible, your car passing its MOT depends on which warning light is showing.

As a rule of thumb, yellow and amber warning lights will be listed as an advisory to be repaired if necessary, unless the problem they’re indicating conflicts with a requirement of the MOT test. The car will likely fail if the low windscreen washer fluid warning is showing, for instance.

Red warning lights, on the other hand, are an automatic fail.

What are the most common warning lights?

So far, we’ve covered what dashboard warning lights are and what they mean in broad terms. Now we’re going to take a more detailed look at five of the warning lights you’re most likely to see and those you should pay particular attention to. Starting with…

Low tyre pressure warning

This indicates that the tyre pressures have dropped below a safe level. It could be that you’ve simply waited too long since pumping them up – or you could have a puncture.

If you see the warning you shouldn’t exceed 50mph until you can find a fuel station to pump up the tyres. When that’s done, you need to reset your car’s tyre pressure monitoring system (TPMS) to clear the warning. Consult your car’s manual to find out how.

The TPMS can give erroneous warnings, but you shouldn’t be complacent. If you see a warning, always stop to pump up your tyres.

Engine temperature warning light

This indicates that your car’s engine is overheating and in danger of breaking down. The most common cause is low engine oil or low coolant, both of which you can refill yourself. Find out how in our guide to taking care of your car.

If the warning comes on repeatedly, it’s likely that there’s a more serious problem and you should take your car to a garage to be fixed. If the warning comes on while driving, stop in a safe place and call a breakdown service. If you continue driving, you run the risk of causing serious damage to your car’s engine.

Low battery charge warning

You’re most likely to see this warning when you start your car, which will probably have been a bit of a struggle as the engine needs a fully charged battery to get going. The most likely cause is simply that your car has an old battery that needs replacing. More seriously, however, it could be that the alternator isn’t charging the battery. Or that a fault is causing electrical equipment to drain the battery.

If the warning comes on whilst driving, stop in a safe place and call a breakdown service. Especially when driving at night, as the car’s headlights could go out. The engine could stop, as well.

ABS failure warning

All modern cars have an anti-lock braking system (ABS) which prevents the tyres from skidding when you have to brake heavily. And it makes cornering while braking much easier. When the warning light comes on, it usually means one of the system’s sensors has failed. The brakes will still work, but not as effectively.

If the warning comes on while driving, stop in a safe place and call a breakdown service. Try to avoid braking heavily while doing so – but if you have to, be aware that your tyres may skid.

Engine management warning

This indicates that the engine management system (or electronic control unit) has detected a fault that’s likely to affect the engine’s performance. There’s a long list of potential causes – including blocked filters and electrical faults.

If the engine management warning comes on while you’re driving it’s likely the engine will go into a low-power ‘limp’ mode that restricts how fast the car can accelerate and also limits its top speed. The more serious the problem, the slower your car will be. Only keep driving if it’s safe to do so, and even then, head for the nearest garage to get the problem fixed. Otherwise, stop in a safe place and call a breakdown service.

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