Car Warning Lights and What They All Mean

Cars can be temperamental at times, and when things go wrong it’s important that the issue is resolved as quickly as possible to prevent a serious problem from occurring.

Thankfully there is an array of dashboard warning lights to let us know when something goes wrong. However, it’s not always clear what they mean. That’s why we’ve put together an A-Z guide of the warning lights you might see and what they mean:

ABS / Anti-Lock Braking System

This indicates an issue with the anti-lock braking system.

The ABS prevents the wheels from locking under severe braking.

Get yourself to a garage.


If the airbag warning light is red it could mean a malfunction with one of the airbags – one of the car’s most important safety features.

Therefore you should stop as soon as possible and take it to a garage.

An amber warning light can signal if the driver has disabled the front passenger airbag.

Battery Charge

This means that the battery is not charging, something is draining its charge or there is a wider issue with the electrical system.

This should be checked out as soon as possible to prevent an unexpected breakdown.

Brake Pad Monitor

This means the system has determined that the brake pads are too thin and need changing.

It is safe to drive with this light on for a short amount of time, however the car should be taken to a garage.

Brake System/Brake Fluid

This suggests there is a fault with the brakes. Firstly, check the handbrake is released fully.

If this does not resolve the issue then there is likely to be a more significant problem. You should drive to a garage as soon as possible to prevent a roadside breakdown.

Broken Bulb

This indicates that a bulb in one of your lights needs replacing.

It is illegal to drive with a faulty or broken headlight, so it is important to change the bulb as soon as possible.

Change Oil

This will notify you that the engine oil needs changing.

You can do this yourself and it’s advisable to change it as soon as possible to avoid causing engine damage.

Cruise Control

The cruise control symbol will illuminate if the system has been turned on. Cruise control helps drivers to maintain a constant speed.

If the light is orange, the speed has not yet been chosen. If the light is green, a speed has been selected.

DEF (Diesel Exhaust Fluid)

This most commonly affects truck drivers, and indicates that the DEF needs changing.

Whilst it is safe to drive with this warning light, you should avoid doing so, as DEF reduces the emissions produced by a diesel engine.

Doors Ajar

This comes on when the system detects that one of the doors isn’t closed properly.

Some cars indicate a particular door that is open, so when it’s safe, stop and close the door.

Diesel Particulate Filter (DPF)

A DPF is found in diesel cars and is used to capture exhaust soot, in order to reduce emissions.

The DPF signal could mean that the filter needs cleaning. Try driving for around ten minutes at fairly high speeds (over 40mph), if it does not solve the problem, take the car to the garage as damage may be caused to the engine.

Electronic Throttle Control

This suggests that the accelerator is faulty. If this warning light comes on, it is best to get checked at a garage quickly.

Engine Cooling System

This suggests that the car is overheating and the coolant level could be low.

To prevent the car from overheating further and causing permanent damage, it is sensible to pull over and call a breakdown service or garage.

Engine Management

If the engine management light comes on, you should have the car checked by a mechanic as soon as possible.

Engine Oil Pressure/Level

This suggests there is a problem with the oil supply or pressure.

It is advisable to pull into the nearest garage or petrol station and check the oil level, filling up if necessary. If the light still shows, contact a breakdown service/garage.

Fog Light

This means your fog lights are on.

Fuel Level

This means the fuel is low, you should go to a petrol station and refill.

Glow Plug

These are found in diesel cars and if illuminated suggests that the plugs are warming up.

In this case the engine should not be started until the light goes off. If it’s flashing it means that an issue has been detected. Take the car to the garage to be checked.


If this light comes on and stays on, then all is well as this means the overdrive is off.

If the light is blinking it means that there is something wrong with the car’s transmission, and you will need to visit a mechanic.

Petrol Cap

This means the petrol cap has not been secured. Best practice is to pull over when safe and ensure it is properly fastened.

Power Steering System

On hydraulic power steering systems, this warning light could indicate low fluid levels.

In a car with an electric system, restarting the engine can often turn the light off. When the power assist is disabled, steering becomes difficult. Taking the car to a garage is the best course of action.

Rear Windscreen Heater

This means that the rear defroster is turned on to clear moisture and improve visibility.

Any flashing means a problem has been detected.

Reduced Power

Also known as ‘limp home mode’, this means the onboard computers have detected a potentially serious fault, and have reduced the engine’s power to prevent further damage.

You should immediately visit a garage to resolve the issue.


This means that one of the passengers does not have their seatbelt on.

The light may be accompanied with chiming or beeping sound. Make sure everyone has their seatbelt fastened.

Security Warning Light

This indicates an issue with the anti-theft system.

Although safe to drive, you should get your car checked out at a garage as soon as possible to avoid security issues.

Service Vehicle

This light may come on when the car detects a fault which requires professional maintenance, or after a set period of time when a service should take place.

Either way, it’s best to get the car checked out to ensure that there are no serious issues.

Traction Control

The traction control system helps your vehicle in difficult conditions and will switch on automatically when it detects a loss of traction.

If the light does not illuminate in slippery conditions then it is best to get the car looked at, as there may be a fault with the system.

Traction Control Malfunction

If this light is on, it means that your traction control system is not functioning correctly.

It is advisable to get this looked at as soon as possible to ensure the car will be safe to drive on slippery surfaces.

Transmission Failure

This warning means that the car’s automatic transmission system has failed.

While it is technically safe to drive with this on, you should get your car checked out as soon as possible.

Automatic transmissions are expensive to replace, and the longer you drive with a fault, the greater the damage you can cause.

Tyre Pressure Sensor/Monitor

If the tyre pressure warning light appears then it suggests your tyre pressure is too low, creating unsafe driving conditions.

It is best to stop at a petrol station or garage to check the pressure and adjust. If this does not solve the issue you will need to visit a garage.

Washer Fluid Level

When the light illuminates it means the washer fluid is low and needs to be refilled.

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