Dashboard warning lights: what each one means
The colour tells you how urgent it is before you know what the symbol means. Red means stop. Amber means get it looked at. Green and blue are just telling you something is switched on.
Colour first, symbol second
You do not need to recognise the symbol to know how worried to be. Dashboard lights follow the same convention as traffic lights, and it is deliberate.
- Red — stop. Something is wrong that can damage the car or put you in danger. Find somewhere safe and switch off.
- Amber or orange — caution. A fault has been detected. You can usually continue, but get it looked at rather than living with it.
- Green or blue — information. A system is switched on and working. Nothing is wrong.
One important exception: a flashing amber engine management light should be treated as red. Flashing usually indicates a misfire that can destroy the catalytic converter within minutes. Reduce speed and stop.
Why they all light up when you turn the key
Every warning lamp illuminates briefly when you switch on the ignition. That is a bulb check, and it is how you know the warning system itself works. They should go out within a second or two of the engine starting.
Two things are worth noticing during that check:
- A light that never comes on at all may mean a blown bulb — and a warning you will never receive. This is an MOT failure for several key lamps.
- A light that stays on after starting is a genuine fault, not a hangover from the bulb check.
If the battery light stays on once the engine is running, that is a charging fault rather than a flat battery — our guide to telling the battery, alternator and starter apart explains what happens next, and the battery health check scores how close yours is to failing.
Tell us what colour it is
If it is red and the car has stopped, get yourself somewhere safe first. Then call — describing the colour and the symbol usually tells us what to bring. We cover jump starts and mobile tyre fitting across North Wales, day and night.
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Questions, answered
What do the colours of dashboard warning lights mean?
They follow traffic light logic. Red means stop, because something can damage the car or put you in danger. Amber or orange means a fault has been detected and you should get it checked. Green or blue is information only, telling you a system is switched on.
Which dashboard warning light is the most serious?
The oil pressure light. It means the engine is not being lubricated properly and an engine can be destroyed within minutes of it appearing. Stop as soon as it is safe and switch off rather than trying to reach a garage.
What does a flashing engine management light mean?
Treat a flashing amber engine light as if it were red. Flashing usually indicates a misfire, which can destroy the catalytic converter in a very short time. Reduce speed and stop somewhere safe. A steady amber engine light is less urgent but still needs reading.
The battery light is on while I'm driving. Is the battery flat?
Not necessarily. That light means the charging system is not delivering, which usually points at the alternator or its drive belt rather than the battery. The car is running on battery reserve and will stop, so head somewhere safe rather than continuing your journey.
Why do all the warning lights come on when I start the car?
It is a deliberate bulb check so you know the warning system works. They should go out within a second or two of the engine starting. A lamp that never illuminates at all may have a blown bulb, which means a warning you would never receive, and that is an MOT failure for several key lights.
Can I drive with the tyre pressure light on?
Check all four pressures cold first, because cold weather alone can trigger it. If a tyre keeps losing pressure you have a puncture and should have it looked at rather than repeatedly reinflating it, as driving on an underinflated tyre damages it internally.
What does the DPF light mean?
The diesel particulate filter is clogging with soot, usually because the car does mostly short journeys. A longer run at sustained speed often clears it. If the light stays on, get it seen before the filter blocks completely, which becomes a much more expensive job.