Car dashboard warning lights - what they mean
Warning lights on dashboard can appear without warning and leave you unsure whether to pull over immediately or carry on driving. This guide covers the most common car dash lights, what each colour means, and the steps you should take to keep yourself and others safe.
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What do the colours of warning lights mean?
Before getting into individual symbols, the colour of a warning light tells you a lot on its own. UK cars broadly follow a traffic light system across the instrument panel.
- Red - stop or take immediate action. Something is seriously wrong.
- Amber/orange - caution required. Get the fault checked soon, but you may be able to keep driving for now.
- Green - a system is active and working normally (for example, cruise control).
- Blue - a specific feature is on, usually full beam headlights.
- White - informational. No immediate action needed.
If you are ever unsure, treat any unfamiliar warning light in car as amber at minimum until you can check your vehicle handbook.
Red warning lights - act straight away
Red warning lights in car almost always mean stop as soon as it is safe to do so. Continuing to drive with certain red lights illuminated can cause serious engine damage or put you in danger.
The most common red lights and what they signal:
- Engine temperature - the engine is overheating. Pull over, switch off, and wait for it to cool before checking coolant levels.
- Oil pressure - oil is not circulating properly. Stop immediately. Running a low-oil engine causes rapid, expensive damage.
- Battery - the charging system has failed. Your car may run for a short time on battery power alone, but it will cut out.
- Brake system - could indicate low brake fluid, a fault with the braking system, or simply the handbrake being left on. Confirm it is not the handbrake before assuming the worst.
- Power steering - steering assistance has been lost. The car can still be steered but will require significantly more effort.
Amber warning lights - get it checked soon
Amber warning lights on dashboard do not usually mean you need to stop immediately, but they should not be ignored for weeks either. Book a check with a garage promptly.
Engine management light (EML) - this is one of the most misunderstood car dash lights. It can indicate anything from a loose fuel cap to a more significant engine fault. If it is flashing rather than steady, treat it as urgent.
Tyre pressure (TPMS) - one or more tyres are below the recommended pressure. Check all four tyres as soon as possible. UK legal tyre tread depth is 1.6mm across the central three quarters of the tyre.
Diesel particulate filter (DPF) - the filter is becoming blocked. A longer motorway run at higher revs can sometimes clear it, but a garage visit may be needed if it stays on.
Glow plug - only on diesel engines. Indicates a fault with the engine pre-heating system, which can make cold starts difficult.
Stability control / ESC - the vehicle's electronic stability control is active or has a fault. A flashing light usually means the system is working; a solid light may indicate a problem.
ABS and brake warning lights
The ABS (anti-lock braking system) light deserves its own mention. A solid amber ABS light means the system has a fault and may not operate in an emergency stop - this makes the car potentially unsafe at higher speeds.
If the ABS light appears alongside the brake warning light, pull over when it is safe to do so and get professional advice before continuing your journey.
What is the engine warning light really telling you?
The engine management light - sometimes called the EML or check engine light on the instrument panel warning light display - is a catch-all symbol. It does not point to one specific problem.
A mechanic can plug a diagnostic reader into your car's OBD-II port (usually found under the dashboard) to pull a fault code and identify the exact issue. Many garages offer this as a low-cost or free initial check.
If the light comes on while you are driving and the car feels and sounds normal, it is reasonable to complete your journey - but book a diagnostic check within a day or two.
Blue and green lights - no panic needed
These lights are informational. They tell you a system is active, not that something is wrong.
- Blue headlight symbol - full beam is on. Remember to dip when oncoming traffic approaches.
- Green seatbelt light - seatbelts are fastened (on some vehicles).
- Green cruise control - cruise control is engaged.
- Green lane assist - lane-keeping assist is active.
If a green light appears that you do not recognise, check your handbook. It is unlikely to indicate a fault.
What to do when a warning light comes on
1. Stay calm. Note which light it is and what colour it is.
2. If it is red, find somewhere safe to pull over promptly.
3. Consult your vehicle handbook - every car has one, and many are available as a PDF online if the paper copy is missing.
4. If the car feels wrong - vibration, loss of power, unusual smell - do not continue driving.
5. Contact a breakdown service or a garage.
Do not cover or ignore a warning light. A fault that costs a small amount to fix today can become significantly more expensive if left.
Warning lights and insurance - what you should know
If you are driving a vehicle that is not your own - perhaps you have borrowed a car, are moving one on behalf of someone else, or are using a car during an emergency - you need to be certain you have valid insurance in place.
Driving with a known serious fault and no valid cover creates a double risk. If you need to insure a borrowed or unfamiliar vehicle quickly, temporary car insurance can be arranged in minutes for periods from an hour upwards.
Learner drivers should also be aware that warning lights behave the same way regardless of who is driving. If a light appears during a lesson or private practice session, treat it with the same urgency. Dedicated learner driver insurance means any fault that arises on a practice drive does not affect the main policy holder's no claims discount.
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Frequently asked questions
Is it safe to drive with an amber warning light on?
In most cases, yes - for a short time. Amber warning lights on dashboard generally mean a fault needs attention soon rather than immediately. That said, you should not ignore them for long. Book a garage check within a day or two. If you are unsure what the light means, consult your vehicle handbook before continuing to drive.
What does a flashing engine warning light mean?
A flashing engine management light is more serious than a steady one. It often indicates a misfire that could damage the catalytic converter. Reduce your speed, avoid heavy acceleration, and get the car to a garage as soon as possible. Do not ignore a flashing EML in the way you might a steady amber light.
Can I fail an MOT because of a warning light?
Yes. Any warning light that is illuminated when it should not be - including the engine management light - is an automatic MOT failure. If you know a light is on before your MOT, it is worth having the fault diagnosed and cleared first to avoid an unnecessary fail fee.
Why has a warning light come on and then disappeared?
Intermittent warning lights are common and can still point to a real fault. The car's onboard computer stores fault codes even when the light is no longer showing. A garage can retrieve those codes with a diagnostic reader. Do not assume the problem has resolved itself just because the light has gone off.
Do warning lights affect my car insurance claim?
Potentially, yes. If you were aware of a serious fault - indicated by a warning light - and continued to drive, your insurer could argue the vehicle was not roadworthy. This might affect any claim you make. Always address red warning lights promptly and keep a record of any faults and repairs.
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