Warning lights: what they mean

Colour first

The colour of a warning light tells how urgent it is. This is a general rule; the owner's manual of your car always comes first.

• Red: possibly a serious or safety problem. Stop the car as soon as it is safe and read the owner's manual.
• Orange or yellow: something is wrong or a system is not working properly. Have it checked soon.
• Green or blue: a system is on or active (for example high beam or cruise control). Not a fault.

Many lights come on briefly when the ignition is switched on as a self-test. If a light stays on after starting, it needs attention.

Red lights

Oil pressure warning: oil pressure may be too low. Driving on can seriously damage the engine. Switch the engine off and check the oil level.

Coolant temperature: the engine may be overheating. Stop, switch off and let it cool. Never open the cooling system cap while the engine is hot.

Brake system or parking brake: the parking brake is still on, the brake fluid is low or there is a fault in the brake system. Check the parking brake first; if the light stays on, do not drive on.

Battery or charging system: the battery is not being charged, for example because of a faulty alternator or belt. You can drive a short while on the battery, but the car may suddenly cut out.

Airbag or seat belt system: the airbag system may be disabled and then will not work in a crash. Have it checked as soon as possible.

Orange or yellow lights

Engine fault (engine symbol): the engine management found a fault. A flashing light is often more urgent, for example misfires that can damage the catalytic converter. Have the fault codes read.

ABS and stability control (ESP): the normal brakes usually still work, but the anti-lock or stability aid does not. Drive more carefully and have it checked.

Tyre pressure (TPMS): one or more tyres may be low. Check the pressure at a petrol station and inflate.

Particulate filter (diesel engine): the filter is filling up. A longer drive at steady speed can help it regenerate; if the light stays on, go to a garage.

Power steering: the steering may become heavy. Drive carefully to a garage.

Hybrid or electric drive: a fault light for the drive system or the high-voltage battery. Follow the message on the display and the owner's manual and consult an authorised garage.

What to do when a light comes on

1. Note the colour and whether the light flashes or stays on.
2. If red: find a safe spot, stop the car and switch the engine off.
3. Look up the symbol in the owner's manual of your car.
4. Check what you can safely check yourself: oil level, coolant, tyre pressure, parking brake.
5. If in doubt, call a breakdown service or garage instead of driving on.

This is a draft and not professional advice. Symbols and meanings differ by make and model. A warning light is an alert, not a diagnosis.