Car dashboard warning lights: what the symbols mean

Decode the meaning of dashboard lights in your car with a full guide to the most common issues

John Evans
Jan 31, 2019

Lurking behind your car's speedometer are a barrage of warning lights, ready to burst into action the moment that an issue crops up.

But with 50 or more different symbols used in some models, understanding what they all mean is virtually a GCSE exam in itself. And then there's knowing what to do if one suddenly appears on your dashboard: stop the car; drive to a garage or continue your journey? Should you trade your car in?

Many lights are self-evident, such as the petrol pump that indicates low fuel, so we've concentrated on explaining some of the most serious and most baffling symbols that you might see popping up on your dashboard. We've looked at specific electric car warning lights and hybrid car warning lights in separate articles.

Several lights illuminate as soon as you turn the car on, showing that the relevant systems are working. They should then go off. If any remain on or light up during your journey, then they demand your attention. The lights are linked to sensors, so an alert can mean that the sensor is faulty or that it has detected a problem. Ignoring a light could lead to serious damage, as well as your car failing its MOT

Dashboard lights are colour-coded so you know how urgently you need to act. In general:

  • Red lights Require immediate action and often relate to safety-critical systems.
    Stop the car and investigate
  • Orange / yellow lights Highlight system errors, information on critical features or low fluid levels.
    These should be resolved as soon as possible and may need professional attention
  • Green / blue / black and white Information messages. Not a fault.

Many of the symbols are standardised and used by every manufacturer, but there are often differences between non-urgent alerts. We have featured common images below, but bear in mind that your car may not use identical lights for the same issues. All should be listed in your car's handbook.

 

Car dashboard warning lights

Click on any of the symbols below to jump to an explanation of what they mean and the best way to respond

Should I sell a car with a warning light?

Some warning lights are easily fixed - it can just be a case of topping up fluids or tyre pressures. If a sensor is at fault, then the fix can be simple too. However, if the warning light indicates a failure of a major component, then it may be time to say goodbye to your car. Diesel particulate filters, for example, are fitted to most modern diesels and tend to be expensive to replace. Motoreasy, a used car warranty company, says that the most expensive DPF it has replaced is for the BMW 1 Series, at £3,145.

 

Trading in a car with a warning light

You don't need to address a warning light to trade in your car, but failing to do so will probably mean that you receive less for it. Any reputable dealership will want to understand why the light is on and how much it will cost to repair - taking the costs into account when making an offer for your vehicle. In extreme cases, where faults will cause an MOT failure and are expensive to repair, your car could be valued extremely low.

Tyre pressure

What to do Stop and check your tyres.
MOT fail? Yes, if sensor is faulty and tyre doesn't just require more air

When you pump up your tyres you should enter the new values into the pressure monitoring system so that when the sensors detect a sudden fall in pressure, they can alert you. A gradual and consistent fall in pressure across all four tyres will not trigger it, so don't use the system to avoid checking your tyre pressures.
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Diesel particulate filter (DPF)

What to do Either take a long, high-speed journey or drive to a garage as soon as possible
MOT fail? Yes

The DPF traps the soot produced by a diesel engine (gasoline particulate filters are being introduced in some new petrol cars, too) so is a key weapon in the fight against pollution. Filters in diesel cars can become clogged if they are used predominantly on short or slow journeys.

The soot can normally be burned off by driving at motorway speeds for several miles unless the DPF is too full. It’s a complex and expensive component so follow the instructions on trying to clear it or take the car to a garage to have it checked.
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Check engine

What to do Take the car to a garage as soon as possible
MOT fail? Yes

Unlike most warning lights, the engine light is not specific to any one problem. It could mean there’s a fault with all sorts of components and sensors. Most are related to the car’s emissions control system so a problem may not be apparent or urgent but you should get it checked as soon as possible. Read more on the most common reasons why the check engine light is on in our separate article.
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Engine oil level

What to do Top-up the oil as soon as possible.
MOT fail? No

As part of your regular maintenance checks, you should check the engine oil level using the dipstick or risk the low level light coming on when the quantity of oil in the engine has fallen to a critical level.
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Brake pads worn

What to do Reduce your speed and have the brake pads - and possibly discs - replaced as soon as possible.
MOT fail? Yes

This symbol can be difficult to distinguish from that for the brake system. The dotted lines represent the brake pads, which grip the brake disc and slow the car down,showing that they are almost completely worn and should be replaced as soon as possible.
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Anti-lock brake system (ABS)

What to do Reduce your speed and drive to a garage immediately.
MOT fail? Yes

This system is a critical safety aid. ABS prevents the wheels locking up under heavy braking in slippery conditions, enabling you to retain steering control and brake in a shorter distance.
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Electronic parking brake fault

What to do Drive to a garage immediately.
MOT fail? Yes

An electronic parking brake is a complex and expensive component. If the warning light comes on, take it to a garage immediately. If you need to stop the car and park it, put it in a high gear with the front wheels pointing at the kerb.
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Stop-start unavailable

What to do Drive as normal. Check the battery if it's on permanently
MoT fail? No

This isn't normally a fault, but your car preventing itself from running the battery down in heavy traffic. The stop-start system automatically turns the engine off when the car is stopped (this happens when you put a manual car into neutral, or come to a halt in an automatic). The car then relies on the battery to power equipment such as the radio and ventilation fan, and to restart it when you move off again. If electricity levels run low, stop-start is disabled until the engine can recharge the battery again. If this is lit permanently, it may indicate that your battery needs replacing.
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Service

What to do Book your car in for a service as soon as possible
MoT fail? No

Servicing your car on time is a mandatory part of many leasing and finance agreements. it's also a good idea in general. Many cars will monitor the time and mileage covered since the previous service and alert you when the next is due.

Other vehicles use condition-based servicing, or variable service intervals. They monitor wear and tear on components, and then calculate when the next service is needed. You'll often see a service symbol with a mileage countdown, showing how far you can drive before the service is due.
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AdBlue low

What to do Top up your car's AdBlue tank
MoT fail? No

Modern diesel cars use an additive, called AdBlue, which is injected into the exhaust where it reacts with toxic pollutants and converts them into harmless air and water. If it runs out between services, then it must be refilled. A yellow symbol indicates that the tank is running low. When it turns red, it needs refilling urgently; the car will fail to start if the AdBlue runs out completely. Not all manufacturers use a bottle. Others show what looks like an ice cream cone lying across a diesel particulate filter.
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Fuel tank cap not fitted properly

What to do Check the cap is secure or replace it.
MOT fail? No

The humble fuel tank cap is a key part of the car’s fuel system since it helps to regulate the air pressure in the fuel tank and maintain an interrupted supply of fuel to the engine. If you've forgotten to replace it after filling up, your car should warn you.
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Electronic stability control

What to do Drive to a garage as soon as possible (when light is permanently on)
MOT fail? Yes

Unlike traction control, below, ESC, as it’s known, uses the brakes to keep a vehicle on the right path, without skidding. If you see it flashing, then it’s in operation and you’ve probably just avoided a hairy situation. When the light remains on, it’s likely to indicate a fault.
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Electronic stability control / traction control off

What to do If you didn't switch it off, have the system checked as soon as possible.
MOT fail? Yes

This symbol applies to the Electronic Stability Control (ESC), which aims to keep the vehicle pointing in the right direction if the wheels start sliding. Traction control helps to prevent the wheels from slipping when you accelerate. Many cars allow you to switch these systems off with a button, which illuminates this warning light. It's easy to see if you've switched it off by accident, and should will also light up if there's a fault that has disabled them.
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Washer fluid low

What to do Top up windscreen washer fluid
MOT fail? yes

A low washer fluid bottle can result in your car failing an MOT, although a good garage would top it up for you to ensure that a minor oversight doesn't require a retest. More importantly, a lack of screenwash could leave you struggling to see, particularly in winter when the sun is low and road salt is splattered across your screen.
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Press clutch pedal

What to do Push the clutch pedal
MOT fail? No

Modern manual cars generally require you to press the clutch pedal when you start the car, which helps to prevent it lurching forward if it's still in gear. If you're not used to this system, then you'll see this light appear in amber or green when you press your car's start button or turn the key. It may also appear if you stall a car with a push-button start: depressing the clutch can restart the engine.

Automatic cars also use a similar symbol that instructs you to put your foot on the brake pedal before starting the car. In this case, there are brackets on the left and right of the circle, indicating that it's brake related.
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Tiredness alert

What to do Take a break
MoT fail? No

Tiredness alerts are fast-becoming a standard feature of cars. Most analyse your steering movements to detect when fatigue is setting in and the driver is less alert. The coffee cup is a common symbol used to encourage you to take a break. The system doesn't prevent you from continuing to drive if you feel up to it.
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Ice warning

What to do Watch out for ice
MoT fail? No

The snowflake symbol tends to appear with a loud chime when the outside temperature drops below 3-4C. At this level, ice can form on the road, so it's a warning to be more cautious.
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Key not detected

What to do Ensure that your key fob is in the front of the car
MoT fail? No

Cars with keyless start buttons will only switch the engine on if the key fob is close to a sensor in the front of the car.If you've left the key in a jacket that's been placed in the boot, you may see this alert to bring the key fob closer.

The warning also helps avoid driving away without the key - if you're dropping off a passenger who has a key in their pocket, for example. The engine doesn't switch off without the key, so it would be easy to drive merrily away and park up, only to find out that you can't restart the car and you're miles away from the key.
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Brake system fault

What to do Stop and check the brake fluid level. If ok, drive at reduced speed to a garage.
MOT fail? Yes

While you can still brake – just – with worn pads, a fault in the braking system itself could suggest total failure is imminent. There may be a fluid leak in the system, the servo that provides the braking effort may be faulty or the brake fluid level may have dropped. If the brake pedal feels spongy, stop driving immediately.
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Engine temperature

What to do Stop the car immediately.
MOT fail? No

This means the temperature of the engine is too high either as a result of insufficient coolant in the system caused by poor maintenance, a broken water pump or a leaky radiator and hoses, or a blown head gasket allowing coolant to escape. Drive any further and you risk destroying the engine.
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Battery charge

What to do If you can, drive to a garage immediately
MOT fail? No

This symbol applies not only to the battery but the whole of the vehicle’s electrical system, including the alternator that generates current. It’s serious because a modern car relies on electricity to power things such as the steering and brakes, as well as lights and the engine itself. If the battery is more than around four years old, it may be at fault.
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Airbag and belt tensioner system

What to do Take the car to a garage as soon as you can.
MOT fail? Yes

The airbags and seatbelt tensioners are key safety components which is why any issue should be checked and resolved as soon as possible.
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Engine oil pressure

What to do Stop the car immediately.
MOT fail? No

Not to be confused with the low engine oil level light, which is amber, with a wavy line underneath the oil can, this one is much more serious since it means oil isn’t being pumped around the engine. Drive any further and you risk destroying the engine.
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Electronic power steering (EPS)

What to do Stop the car and request assistance.
MOT fail? Yes

Without power assistance, modern cars are almost impossible to steer which is why it’s vital that when you see this warning light you take no chances and stop in a safe place immediately.
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