Dashboard warning lights explained: what each one means
The short answer
The quick rule is colour. A red light means there's a problem that could damage the car or leave you stranded, so stop as soon as it's safe. An amber or orange light means something needs looking at soon but isn't usually an emergency. A green or blue light is just telling you a system is on, like your lights or cruise control, and needs no action.
Modern cars can throw up dozens of different symbols and it's not always obvious which ones mean pull over now and which can wait until the weekend. Below are the lights people ask us about most, what each one is actually telling you, and how seriously to take it.
Common causes and what they mean
A few things could be behind it. Here's what each usually points to, and how serious it is.
Oil pressure (red oil can)
One of the most serious. It means the engine may be losing oil pressure, which can wreck the engine in minutes. Stop as soon as it's safe, switch off, and check the oil level before driving any further.
Battery / charging (red battery)
The charging system isn't keeping the battery topped up, usually a failing alternator or belt. The car will keep going until the battery runs flat, then stop, so get it checked quickly rather than risk being stranded.
Engine management (amber engine)
The car has logged a fault in the engine or emissions system. Steady amber with the car driving normally is usually safe to get home on, but have it read soon. Flashing, or running rough, means stop and get it checked.
Coolant temperature (red thermometer)
The engine is overheating, often from a coolant leak, a failed thermostat or a water pump. Keep driving and you can warp the head. Pull over, let it cool, and don't remove the cap while it's hot.
Brake, ABS, tyre pressure, airbag
A red brake light can mean low brake fluid or just the handbrake left on, and low fluid affects how well the car stops, so don't ignore it. The amber ABS and tyre pressure lights mean that system needs checking soon but the car is usually still driveable. The airbag light is often red and means the airbag may not go off in a crash, so the car drives normally but get it looked at.
Which lights mean I have to stop?
Treat colour as your guide. A red light means stop as soon as it is safe to do so, especially oil pressure, coolant temperature or brake, because carrying on can cause serious and expensive damage. An amber or orange light means the car is telling you to get it checked soon, not that you have to abandon the journey, though a flashing amber engine light is the exception and should be treated as a stop. If you're ever unsure what a light means, it's cheaper to ask than to guess.
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