Dashboard warning lights are vitally important. They will alert you if your car’s mechanical or safety systems aren’t working correctly – and they can result in MOT failure if illuminated.
Lights can be split into three categories. Red usually means ‘bad’ problems, orange or yellow is advisory and blue or green cover everything else. Generally speaking, whether it’s a solitary 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.
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.
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 get a mechanic to investigate.
Low oil pressure
A light which 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.
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. I
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.
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 indicates when the engine gets too hot and looks like a thermometer with wavy lines.
Like the oil pressure warning light, you should stop and turn off the car’s engine to prevent further damage.
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.
Occasionally you might see this light appear for a brief moment while driving. Most likely to illuminate in slippery or wet 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.
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.
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.
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.
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.
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.
Some cars will display a warning light when they detect a failed bulb in one of the car’s lights. Replace the bulb to extinguish the light.
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.
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.
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.
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.
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.
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.