Understanding Dashboard Warning Lights and What They Mean

The Colour Code: Red, Amber and Green

Your dashboard is a conversation between you and your car. Warning lights use a simple colour code to tell you how urgent that conversation is. Red means stop as soon as it is safe to do so — something serious could be wrong. Amber means caution: the car needs attention, but you can usually continue to a garage if it feels normal. Green or blue lights simply confirm a system is on, such as headlights, indicators or cruise control. When a light appears, don’t panic. Check your handbook for the exact symbol, because it varies between models. The handbook is the final word for your car.

Red Warning Lights: Stop Safely and Investigate

Red lights are the ones that deserve immediate action. Pull over in a safe place, switch off the engine and investigate. Driving on can turn a small repair into a very large bill.

• Oil pressure — a red oil can symbol means the engine may not be getting enough oil. Stop immediately, switch off and check the oil level on level ground. If it is low, top up with the correct grade. If the light stays on, do not restart the engine; call for recovery.
• Coolant temperature — a red thermometer or coolant symbol means the engine is overheating. Stop, let it cool completely, then check the coolant level in the expansion tank. Never open the cap while hot. If you have to top up frequently, there is likely a leak.
• Brake system — a red circle with an exclamation mark or the word “BRAKE” can mean the handbrake is on, low brake fluid, or a serious braking fault. If the pedal feels spongy, the car pulls to one side, or the light stays on after releasing the handbrake, stop and call for help.
• Battery charging — a red battery symbol usually means the alternator is not charging. You may be running on battery power alone. Switch off unnecessary electrics and drive straight to a garage if the car feels normal, but be prepared for it to cut out.

Amber Warning Lights: Book It In Soon

Amber lights are a nudge, not a siren. They usually mean a fault has been detected and you should arrange a diagnostic check soon. If the car drives normally, you can often continue carefully — but don’t ignore it for weeks.

• Engine management light (MIL) — a steady amber engine symbol means the engine or emissions system has a fault. It could be a loose fuel cap, a sensor issue or something more serious. A flashing engine light is different: stop as soon as safe, because it often indicates a misfire that can damage the catalytic converter.
• ABS and traction control — amber ABS or a car with squiggly lines means the anti-lock braking or stability system is disabled. Normal brakes still work, but you should leave extra stopping distance and get it checked. It may be a wheel sensor or a dirty connector.
• Diesel particulate filter (DPF) — common on UK diesels, this amber light means the filter is partly blocked. A steady 40–50 mph run for 20–30 minutes can help it regenerate, but short town trips make it worse. If it stays on, book a garage visit.
• Tyre pressure monitoring — an amber horseshoe with an exclamation mark means one or more tyres are under-inflated. Check pressures when cold and inflate to the figures in your handbook or door pillar. Reset the system if your car has a reset button.
• AdBlue — on many modern diesels, an amber AdBlue warning means the level is low. Top up with the correct specification, but don’t overfill. If it runs dry, the car may refuse to start.

Lights You Can Usually Sort Yourself

Some warnings are simple maintenance reminders. A washer fluid light means top up the reservoir with screen wash — important in UK winters. A fuel cap light often means the cap is loose or the seal is dirty; tighten it and the light may clear after a few trips. A service due light is a reminder, not a fault. A bulb failure light means check all exterior lights, including brake and number plate bulbs. Keep a spare set of bulbs in the boot, as driving with a failed brake light is illegal. For tyre pressure, use a reliable gauge at a petrol station or your own compressor, and check the spare too.

When to Keep Driving and When to Pull Over

Use the light colour plus how the car feels. If it is red, stop. If it is amber and the car drives normally — no loss of power, no unusual noises, no smoke, no burning smell — you can usually drive to a garage. But if an amber light appears alongside rough running, vibration, reduced power, overheating, or a smell of fuel or burning, pull over and investigate. If several lights come on at once, or the car enters limp mode, stop safely. Never clear fault codes without fixing the problem; the light will return, and you may mask a serious issue. Your safety and other road users come first.

Staying Calm and Prepared

Keep your handbook in the glovebox and read it when you have a quiet moment. A basic OBD-II code reader can help you understand an engine light before you visit a garage, but it is not a substitute for proper diagnosis. Check oil, coolant, screen wash and tyre pressures weekly, and keep up with servicing and MOT dates. Learn what “normal” looks like on your dashboard, so a new light stands out. If in doubt, stop and ask. A few minutes of caution can save you hundreds of pounds and keep you safe on UK roads.