Dashboard Warning Lights Explained: Red, Amber and Green

What the colours mean

Dashboard warning lights follow a simple colour code. Red means a serious problem, so stop as soon as it is safe and do not carry on driving. Amber or yellow means something needs checking soon, but you can usually drive carefully to a garage. Green and blue lights are just telling you something is switched on, like your headlights or cruise control.

It is normal for lots of lights to come on briefly when you turn the ignition on. That is the car checking its bulbs and systems. They should all go out within a few seconds of the engine starting. A light that stays on, or comes on while driving, is the one to pay attention to.

Never simply ignore a light because the car seems to drive normally. Many faults, such as an oil pressure or airbag problem, give no other warning until something goes wrong. Equally, do not panic. Plenty of amber lights turn out to be something simple like a loose fuel cap, a faulty sensor or a tyre that needs air. The key is to note the colour, whether the light is steady or flashing, and whether the car feels any different, and then get it looked at in the right timeframe.

Red warning lights: stop safely

Oil pressure warning, usually shaped like an old oil can: the engine may not be getting enough oil. Stop and switch off straight away, as driving on can wreck the engine within minutes. Check the oil level once it has cooled, but do not restart if the light stays on.

Engine temperature warning, a thermometer in liquid: the engine is overheating. Pull over, switch off and let it cool. Never open the coolant cap while it is hot.

Brake system warning, often an exclamation mark in a circle or the word BRAKE: first check the handbrake is fully off. If it stays on, it can mean low brake fluid or a brake fault, which is a safety risk.

Battery or charging warning, a battery symbol: the charging system is not working, so the car is running on battery power alone and will eventually cut out. Power steering and airbag warnings can also show in red on some cars and need prompt attention.

Amber warning lights: get it checked

Engine management light, shaped like an engine outline: the car has detected a fault with the engine or emissions system. If it is on steadily, get it checked soon. If it is flashing, that usually means a misfire, which can damage the catalytic converter, so ease off and have it looked at as soon as possible.

ABS warning: the anti-lock braking system has a fault. Your normal brakes should still work, but the anti-lock function may not, so leave extra stopping distance.

Airbag warning: there is a fault in the airbag or seatbelt tensioner system, and the airbags may not work in a crash. Tyre pressure warning: one or more tyres may be low, so check pressures and look for a puncture.

Diesel owners may also see a DPF light, meaning the diesel particulate filter is getting blocked, and a glow plug light, a coil symbol. The glow plug light normally comes on briefly before starting, but if it flashes or stays on while driving, there is a fault to check.

Green and blue lights

These are information lights rather than warnings. Green usually shows dipped headlights, sidelights, indicators, fog lights or cruise control being active. The blue light is main beam, which is worth watching so you remember to dip for oncoming drivers.

Some cars also show symbols for eco mode, stop-start or lane assist. Your handbook has the full list for your car, as symbols can vary a little between makes.

Warning lights and your MOT

Several warning lights can cause an MOT failure if they are showing a fault. These include the engine management light, ABS, airbag, brake fluid, power steering and, on cars first used from 2012 onwards, the tyre pressure warning. So a light you have been living with may become a bigger problem at MOT time.

Why a proper diagnostic check helps

When a warning light comes on, the car stores a fault code. A diagnostic scan reads that code, but the code only points to an area, not always the exact part. Replacing parts based on a code alone can waste money, so good diagnosis means checking and testing to confirm the real cause.

If a warning light has appeared on your dashboard, bring the car to MF Autocentre in Walsall. We will read the codes, track down the cause and explain it in plain English. Call 01922 636820 or book online.