What do your car dashboard warning lights mean?

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Our guide to dashboard warning lights

Don’t ignore your dashboard warning lights. They will alert you if your car’s mechanical or electronic systems aren’t working properly – and they can result in MOT failure if illuminated.

The lights can be split into three categories. Red usually means serious problems, orange or yellow is advisory and blue or green cover everything else. Generally speaking, whether it’s a single light, or your dashboard is lit up like a cul-de-sac at Christmas, you should address the issue swiftly.

This is a general guide to dashboard warning lights and what they mean. For more detail, you may need to consult your car’s handbook.

Let’s deal with the red issues first – as you should when you see them.

Battery

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Car dashboard warning lights: everything you need to know

A red warning light in the shape of a square car battery showing positive and negative terminals indicates an issue with charging the battery.

This could be a problem with the battery itself, or the alternator or alternator belt.

Brakes

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Brake

A brake warning light could be triggered by something as simple as the handbrake being on.

If it doesn’t turn off when you disengage the handbrake, check the brake fluid level or ask a mechanic to investigate.

Low oil pressure

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Low oil pressure

A light that looks like an oil can signifies low oil pressure. You should not drive with this light illuminated as it may cause damage to the engine.

Turn the engine off and check the oil level using the dipstick – it may need topping up. Seek assistance if the light stays on.

Seat belt

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Seat belt

A light showing a person sitting with a seat belt across their chest is warning you that someone in the car is not wearing their seat belt. 

f you don’t wear a seat belt and you haven’t got a valid reason, you could be hit with a £100 on-the-spot fine. The driver is also responsible for any children aged 14 or under not wearing their seat belt.

Coolant temperature

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Coolant temperature

You should keep an eye on your car’s temperature gauge to identify any issues with its cooling system, but some cars also have a temperature warning light. This looks like a thermometer with wavy lines and indicates when the engine gets too hot.

Like the oil pressure warning light, you should stop and turn off the car’s engine to prevent further damage.

Airbag

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Airbag

A light showing a person with a circle in front of them suggests there’s a fault with one of the car’s airbags. Investigate it as soon as convenient.

Door open

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Car door open warning light

This one is pretty self-explanatory. It could be one of the doors, the boot or the bonnet open, depending on the symbol shown.

If you see this light while driving, pull over safely and make sure the relevant door is closed.

Washer fluid

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Washer fluid

We’re now moving onto orange or yellow lights, which signify advice rather than urgent issues.

A shortage of washer fluid can trigger a warning light on some cars. Simply top up the washer fluid reservoir to turn the light off.

Traction control

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Traction control

Occasionally you might see this light appear for a brief moment while driving. Most likely to illuminate in wet or slippery conditions, the traction or stability control light means the car is having to brake a wheel or cut power to prevent wheelspin or skidding.

Driving more cautiously with the conditions in mind will prevent it appearing again.

ABS

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ABS

The ABS light is likely to come on during hard braking. This is when the anti-lock braking system is triggered. Essentially, during heavy braking the system will modulate the brakes to prevent the wheels locking up and causing a skid.

As with traction control, if this kicks in on the road, adapt your driving to prevent it.

Engine management

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Engine management

The engine management or ‘check engine’ light could mean a wide range of things, from an open fuel filler cap to a serious engine problem.

You’ll need to plug a diagnostics reader into your car to establish exactly what the issue is.

Tyre pressure

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Tyre pressure warning light

If you car is fitted with a TPMS (Tyre Pressure Monitoring System), you may see this light when one or more of the tyres is under-inflated – possibly due to a puncture.

An under-inflated tyre will wear more quickly, lead to higher fuel consumption and cause the steering to feel sluggish. It may also make the car dangerous to drive.

If the TPMS light flashes for a minute or so when you start the car and then stays on, this means the system isn’t working properly. Get it checked at a garage as soon as you can.

Catalytic converter

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Catalytic converter warning light

A catalytic convertor uses chemical reactions to break down harmful gases in your car’s exhaust. This light means it is overheating or not functioning correctly.

You can continue driving with this light illuminated, but you should have the issue investigated promptly – or risk further damage to the ‘cat’ (and a potentially bigger bill).

Service warning

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Car service warning light

The exact appearance of this warning light may vary, but it’s there to warn you that your car is due a service.

The service schedule will be detailed in the handbook, and you should follow it closely to keep your car safe and preserve its future value. Many modern cars will actually give you a mileage countdown until the service is due.

Lane assist

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Lane assist

If your car is fitted with lane assist – to nudge you back into lane if your car starts to drift on the motorway – a light might display to show it’s enabled.

Cruise control

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Cruise control

If your car is fitted with cruise control, a light showing a car’s speedo with an arrow pointing at it might display when the system is turned on.

Glow plugs

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Glow plugs

If you drive a diesel car, a glow plug light might display when you first turn the key. This means the glow plugs are warming up and the ignition shouldn’t be turned on until the light goes out.

If the light flashes, it suggests a problem with the glow plugs.

Bulb failure

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Bulb failure

Some cars will display a warning light when they detect a failed bulb in one of the lights. Replace the bulb to extinguish the light.

DPF

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DPF

If you drive a modern diesel car, it might display a DPF light when the diesel particulate filter becomes blocked.

This is most likely to happen if you do lots of short journeys at low speeds. Allow it to regenerate by driving on a long motorway journey.

Indicators

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Indicators

When you turn your indicators or hazard lights on, left or right arrows will display on the dash to show which way you’re indicating.

Main beam

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Main beam

When you’ve got main beam engaged for driving in the dark, a blue light like the one in the picture above will display on your dashboard.

You should make sure you dip your headlights when there are other cars about to prevent oncoming drivers being blinded.

Fog lights

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Fog lights

A curved ‘D’ shape next to wavy lines will indicate that your front or rear fog lights are turned on. These should only be used when visibility drops below 100 metres.

Stop/start

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Stop/start

An exclamation mark below a curved arrow relates to the car’s stop/start system. Depending on the car, it could mean that the system is turned on, allowing the engine to turn off when the car is stopped to save fuel, or simply turned off.

It could also mean there’s an issue with the stop/start – consult your owner’s manual if unsure.

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