Explanation of warning lights on car dashboard

You have probably noticed that when you start a car, a lot of symbols light up on its dashboard. The lights usually go out when the engine is started. You may also see some of the symbols light up while driving.

It is not always clear what exactly the symbols mean, so it can be difficult to understand what they are talking about. Here's our guide to what car warning lights mean and what to do about them.

What do the warning lights on the dashboard mean?

When the warning light comes on, it indicates that the condition of your vehicle has changed in a way that requires attention and may even affect your ability to continue driving safely.

Light takes the form of a symbol or word that illustrates the problem. If your vehicle has a digital driver display, you may also see a text-based warning explaining the problem. 

There are some warning lights that every car has and others that are equipment that only some cars have. The symbols and words used are generally the same for all cars, although manufacturers use different variations of the less common ones. We'll look at common signal indicators - the ones you're most likely to see - in more detail later.

What causes warning lights to come on?

Not every light on your car's dashboard is actually a warning light. You are probably familiar with the green and blue symbols to indicate that your vehicle's lights are on and the yellow fog lamp symbols.

Most of the other indicators on your car's driver display indicate that there is some kind of problem. Each one relates to the part of your vehicle that has the problem. 

Some of them are quite easy to solve. For example, a yellow fuel pump indicator indicates that the car is running out of fuel. But other warning lights point to more serious problems. Most of these relate to low fluid levels or an electrical problem.

Many of the driver safety systems in recent cars also show a warning light when they are activated. Lane Departure Warning and Forward Collision Warning Lights are some of the things you're most likely to see. You will also see the light if one of the doors is not closed properly or if one of your passengers is not wearing a seatbelt.

Can I continue driving if the warning light comes on?

Each warning signal requires you, as the driver, to take some action. Depending on the problem, you may experience changes in the way you drive and may need to start looking for a safe place to stop. You should at least slow down to a safe speed if necessary. 

Many modern vehicles with a digital driver display will display a message with advice on what you should do when the warning light comes on. The severity of the problem is usually indicated by the color of the warning light. A yellow light means that there is a problem that needs to be solved as soon as possible, but the car is not going to stop. Typical amber lights include a low fuel indicator and a low tire pressure warning. If necessary, slow down and start searching for a gas station.

A yellow or orange light indicates a more serious problem. Again, the car is not going to stop, but the engine can go into low power mode, which causes the car to slow down to prevent serious damage. Typical orange warnings include an engine control light and a low oil level light.

A red light means there is a serious problem that could affect your ability to drive safely. You must stop at the first safe place you can find, then call the emergency services and take the car to the garage for repairs. Typical red lights include an ABS (anti-lock braking system) failure warning and a triangular symbol that simply means "stop".

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

You should always fix any problems that occur with your car as soon as possible. There are some problems indicated by warning lights that you can solve yourself, such as refueling, inflating tires and topping up oil.

If there is a problem that you cannot fix or even identify, you should take the car to the garage as soon as possible.

Are warning lights an MOT fault?

Ideally, you should fix any problems before passing the inspection, regardless of whether there is a warning light. If this is not possible, your vehicle passes inspection, depending on which warning light is on.

As a general rule, amber and amber warning lights are indicated as an advisory for repair if necessary, as long as the problem they indicate does not conflict with the MOT test. The vehicle is more likely to break down if, for example, a low windshield washer fluid warning is displayed.

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

What are the most common warning lights?

So far, we've looked at what dash lights are and what they mean in a broad sense. Now we're going to take a closer look at the five warning signs you're most likely to see, and the ones you should pay close attention to. Beginning with…

Tire pressure warning

This indicates that the tire pressure has fallen below a safe level. You may have just waited too long since pumping them up, or you may have a puncture. 

If you see a warning, do not exceed 50 mph until you find a gas station where you can inflate your tires. When this is done, you will need to reset your vehicle's tire pressure monitoring system (TPMS) in order to clear the warning. Consult your vehicle owner's manual for instructions on how to do this.

The TPMS system may give false warnings, but don't be complacent. If you see a warning, always stop to pump up your tires.

Engine temperature warning light

This indicates that your vehicle's engine is overheating and may fail. The most common cause is low engine oil or low coolant, both of which you can top up yourself. Find out how to do this in our car care guide.

If the warning appears repeatedly, there is probably a more serious problem and you should take the car to the garage to have it fixed. If the warning comes on while driving, stop in a safe place and call the emergency services. If you continue driving, you risk serious damage to your vehicle's engine.

Low Battery Warning

You will most likely see this warning when starting the car, which is likely to be a daunting task as it requires a fully charged battery to start the engine. The most likely cause is that your car has an old battery that needs to be replaced. Seriously though, the alternator is not charging the battery. Or that a malfunction causes the battery to discharge electrical equipment.

If the warning comes on while driving, stop in a safe place and call the emergency services. Especially when driving at night, as the headlights of the car may go out. The engine could also stop.

ABS warning

All modern cars are equipped with an anti-lock braking system (ABS) that prevents tire slippage during heavy braking. And it makes cornering much easier when braking. When the warning light comes on, it usually means that one of the sensors in the system 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 the emergency services. While doing this, try to avoid hard braking, but if necessary, be aware that your tires may slip.

Engine control warning

This indicates that the engine management system (or ECU) has detected a problem that may affect engine operation. There is a long list of potential causes, including clogged filters and electrical problems.

If the engine management warning appears while driving, it is likely that the engine will go into a low power "mode" which limits the vehicle's acceleration rate and also limits its top speed. The more serious the problem, the slower your machine will be. Only continue driving if it is safe to do so, and even then, head to the nearest garage to have the problem fixed. Otherwise, stop in a safe place and call the emergency services.

If you want to be sure that your car is in the best possible condition, you can check your car for free at Kazu Service Center. 

Cazoo service centers offer a full range of services with a three-month or 3,000-mile warranty on any work we do. Request booking, simply select the service center closest to you and enter your vehicle's registration number.