What your dashboard warning lights mean
Red, amber, green and blue: what the 30 most common warning lights mean, and what to do when one comes on.
A light on the dashboard is the car telling you something, and the colour tells you how soon to listen. Read the colour first, then the symbol.
Colour first
- Red: act now. Something needs attention before you drive on. Stop when it's safe, switch off if the light says so, and find out why.
- Amber: check soon. The car has found a fault or something is running low. You can usually keep going carefully, but book a check.
- Green and blue: for information. A system is on: the headlights, the cruise control, main beam. Nothing is wrong.
Lights differ between makes, so your owner's manual has the exact meaning for your car. The tables below cover the 30 lights you're most likely to see.
Red: act now
| Light | What it means | What to do |
|---|---|---|
 Oil pressure | The engine has lost oil pressure. Running it like this can destroy the engine within minutes. | Stop safely as soon as you can and switch off the engine. Check the oil level when it has cooled. Do not drive on until it is fixed. |
 Engine temperature | The engine is overheating. | Stop safely and switch off the engine. Let it cool before checking the coolant: never open the cap while it is hot. Get it checked before driving far. |
 Battery charging | The battery isn’t being charged, usually an alternator or belt fault. The car can stop once the battery runs flat. | Switch off what you don’t need (air conditioning, heated seats, radio) and drive straight to a garage. Avoid switching the engine off on the way. |
 Brake system | The parking brake is on, or, if it stays lit once released, the brake fluid is low or the brakes have a fault. | Release the parking brake. If the light stays on, stop safely and don’t drive: have the brakes checked. |
 Airbag | The airbag system has a fault: the airbags may not work in a crash. | You can drive, carefully. Have it checked soon, and don’t seat a child in the front meanwhile. |
 Power steering | The power steering has a fault. Steering can become very heavy. | Drive slowly and carefully to a garage, holding the wheel firmly. If steering is very heavy, stop and call for help. |
 Seat belt | Someone in the car isn’t wearing a seat belt. | Fasten every seat belt before driving off. |
 Door open | A door, the boot or the bonnet isn’t fully closed. | Stop and close it properly before driving on. |
 Gearbox temperature | The automatic gearbox is overheating, often after heavy traffic, towing or a long climb. | Stop safely, put it in Park and let it cool with the engine idling or off. If it comes back, have the gearbox checked. |
 Hybrid or electric system | The high-voltage system has a fault. | Stop safely and call roadside assistance. Don’t try to fix it yourself: it runs at high voltage. |
Amber: check soon
| Light | What it means | What to do |
|---|---|---|
 Check engine | The engine computer found a fault. Steady: have it checked soon. Flashing: the engine is misfiring and can damage the catalytic converter. | Steady: book a check soon. Flashing: slow down, avoid hard acceleration and have it checked straight away. |
 ABS | The anti-lock braking system has a fault. Normal braking still works, but the wheels can lock in an emergency stop. | Drive carefully and leave more distance. Have it checked soon. |
 Tyre pressure | At least one tyre is under-inflated. | Check and inflate the tyres to the pressure on the door frame sticker. If it comes back soon, a tyre may have a puncture. |
 Stability control | Flashing: the system is working to keep grip on a slippery road. Steady: it is switched off or has a fault. | Flashing: ease off and drive gently. Steady: switch it back on; if it stays lit, have it checked. |
 Glow plugs (diesel) | On a diesel, the engine is warming up to start. Flashing while driving means a fault. | Wait until it goes out before starting the engine. If it flashes while driving, have it checked. |
 Particulate filter (diesel) | The diesel particulate filter is getting blocked, usually from many short trips. | Drive for 15 to 20 minutes at a steady speed on a fast road to let it clean itself. If the light stays on, see a garage. |
 Low fuel | The tank is nearly empty. | Fill up soon. Running out can damage the fuel pump. |
 Washer fluid | The windscreen washer fluid is low. | Top it up at the next stop. |
 Service due | The car’s own reminder that a service is due. | Book the service. After it, the garage resets the reminder. |
 AdBlue (diesel) | The AdBlue (diesel exhaust fluid) tank is running low. | Refill soon. Many diesels won’t restart once the tank is empty. |
 Brake pad wear | The brake pads are worn down to their sensor. | Have the pads replaced soon, before they damage the discs. |
 Light failure | An exterior bulb (headlight, brake light or indicator) has failed. | Walk round the car to find it and replace the bulb. |
 Low oil level | The engine oil level is low (oil pressure is still fine). | Top up with the oil grade in your manual soon, and watch for a leak. |
 Frost warning | The outside temperature is near freezing: roads may be icy. | Drive gently and leave more room to stop. |
 Key battery | The battery in the key fob is running low. | Replace the key battery soon (usually a coin cell). |
For information
| Light | What it means | What to do |
|---|---|---|
 Main beam | The headlights are on full beam. | Dip them for oncoming traffic and when following another car. |
 Headlights on | The dipped headlights are on. | Nothing to do. |
 Fog lights | The fog lights are on. | Switch them off when visibility is good again: they dazzle other drivers. |
 Cruise control | Cruise control is on and holding your speed. | Nothing to do. Tap the brake to switch it off. |
 Ready (hybrid or electric) | The car is on and ready to move, even though there may be no engine noise. | Nothing to do. Switch off fully before leaving the car. |
Steady or flashing
A flashing light is usually more urgent than a steady one. The check engine light is the classic case: steady, have it checked soon; flashing, the engine is misfiring, so slow down and get it looked at straight away.
When a light comes on
- Note which light it is, its colour, and whether it's steady or flashing.
- If it's red, stop when it's safe. If it's the oil pressure or the temperature light, switch off the engine.
- Look the symbol up in the owner's manual.
- Have it checked, sooner for red, soon for amber. If you're unsure, treat it as red.