What do the warning lights on my dashboard mean?

There are far too many symbols to memorise and manufacturers do not use identical ones. The colour convention, though, is consistent across every car sold in the UK, and it is enough to decide what to do in the moment.

Safety

Step by step

1. Note the colour first.Before trying to identify the symbol, look at whether it is red, amber or green. That alone tells you whether to pull over, book a garage, or ignore it entirely.
2. Treat red as stop.Find somewhere safe, pull over and switch off. Red covers oil pressure, coolant temperature, brake faults, charging failure and airbag faults — none of which improve by carrying on.
3. Know the four reds that matter most.An oil can symbol means low oil pressure and can destroy an engine in minutes. A thermometer means overheating. A circle with brackets, or the word BRAKE, means a brake system fault. A battery symbol means the car is running on the battery alone and will stop when it is flat.
4. Treat amber as book it in.Engine management, tyre pressure, particulate filter, ABS and traction control warnings are ambers. Drive gently, avoid heavy loads and long trips, and get it read soon.
5. Ignore green and blue.Headlights, main beam, indicators, cruise control, fog lights. They tell you a system is on, and the only useful reaction is checking you meant to switch it on — rear fog lights in particular.
6. Watch for flashing.A flashing engine management light usually means a misfire that is dumping unburnt fuel into the catalytic converter. Reduce speed and load and get it seen quickly, because that damage is expensive.
7. Check the obvious before panicking.A brake warning is often just the handbrake left partly on. A door light means a door not shut. Check the simple explanation before assuming the worst.
8. Look up the symbol in the handbook.Every handbook has a warning lights section with the exact symbols for your car. Photograph those pages and keep them on your phone.
9. Have codes read rather than guessed.Any garage, and most parts shops, will read fault codes from the car. It costs little and replaces guesswork with a starting point.
10. Never simply clear a light and carry on.Clearing the code removes the symptom, not the fault. It will come back, and in the meantime you have lost the information the car was giving you.

Tips

• All the lights coming on briefly when you turn the key is a self-test and is normal. What matters is which ones stay on.
• Photograph the dashboard when a light appears. It is far more useful to a garage than a description from memory.
• A tyre pressure warning is amber but often the easiest thing on the list to fix yourself in five minutes.

Common mistakes

• Driving on with a red oil or temperature light to reach a garage — Both faults destroy engines quickly. The few miles saved cost far more than a recovery truck, and in the case of oil pressure the damage can be done within minutes.
• Assuming an engine management light means the car is unsafe — It usually means an emissions or sensor fault. It should be investigated promptly, but an amber light with the car driving normally is not a reason to abandon it at the roadside.

If it doesn't work

Questions people ask