Car warning lights explained: what each colour means
Updated 4 min readSources: GOV.UK
Quick answer
Red usually means a serious problem: stop somewhere safe and find out what it is. Amber usually means something needs checking soon. Green or blue usually shows a system is switched on. Lights should come on when you start the engine and go out; if one stays on or appears while you drive, stop and investigate. Your handbook is the final word.
Key facts
- Red
- Serious: stop safely and find out why
- Amber (orange or yellow)
- A fault or service due: get it checked soon
- Green or blue
- A system is on, such as main beam. Not a fault
- The Highway Code says
- Understand every light and do not ignore warning signs
In this article
What the colours mean
- Red
- Something serious: a safety-critical system or a fault that can cause damage. Stop in a safe place and find out what it means before you carry on.
- Amber (orange or yellow)
- A fault or warning that needs attention soon. You can often drive carefully to a garage, but do not leave it. A flashing light is more urgent than a steady one.
- Green or blue
- A system is switched on, such as the headlights, main beam or cruise control. This is information, not a fault.
The common warning lights and what to do
| Light | What it usually means, and what to do |
|---|---|
| Oil pressure (red oil can) | Means: oil pressure has dropped or the oil level is very low. Do this: stop as soon as it is safe and switch the engine off. Do not keep driving; get advice or recovery. |
| Battery or charging (red battery) | Means: the battery may not be charging. Do this: head for a garage. The car can stop when the battery runs flat. |
| Engine temperature (red thermometer) | Means: the engine is overheating. Do this: stop safely and let it cool. Do not open the radiator cap or expansion tank while it is hot. |
| Brake system (red circle with an exclamation mark) | Means: handbrake still on, low brake fluid, or a brake fault. Do this: check the handbrake is off. If the light stays on, do not drive on; get it checked. |
| Airbag or seatbelt (red figure with a circle) | Means: a fault in the airbag or seatbelt system. Do this: get it checked soon. The airbags may not work in a crash, and it can also affect the MOT. |
| Engine management (amber engine outline) | Means: a fault in the engine or emissions system. Do this: if steady, get it diagnosed soon. If it flashes, or the car runs roughly, slow down and get help. |
| ABS (amber letters ABS) | Means: a fault in the anti-lock braking system. Do this: get it checked soon. The normal brakes should still work, but ABS may not. |
| Tyre pressure (amber tyre with an exclamation mark) | Means: a tyre is under-inflated, or the system has a fault. Do this: check the pressures when the tyres are cold and set them to the manufacturer's figures. |
| Stability or traction control (amber car with wavy lines) | Means: it flashes while the system is working and stays on if there is a fault. Do this: a flash on a slippery road is normal. If it stays on, get it checked. |
| Diesel particulate filter (amber filter outline) | Means: the filter is clogged. Do this: your handbook may suggest a longer drive at steady speed. If the light does not go out, get it checked. |
Warning: Symbols and colours differ between manufacturers. Your handbook shows every light on your car and is the final word.
What the Highway Code says
- Make sure you understand the meaning of all warning displays on the instrument panel, and do not ignore warning signs: they could indicate a dangerous fault developing.
- When you start the engine, the warning lights come on and go out (except the handbrake light until you release it). If they do not, or if they come on while you are driving, stop and investigate the problem.
- If the charge warning light comes on while you are driving, it may mean that the battery is not charging.
Warning lights and the MOT
The MOT checks several warning lights: airbags and seatbelt pretensioners, ABS, electronic stability control, the electronic parking brake, brake fluid and electronic power steering. On vehicles first used on or after 1 January 2012 it also checks tyre pressure monitoring. A light that stays on can lead to a fail. See what an MOT checks.
When to get help straight away
A red light is not a wait-and-see. Nor is a light that comes with a change in how the car drives: a pull when braking, loss of power, grinding noises or a burning smell. Stop somewhere safe and call your breakdown provider or a garage.
Common questions
Can I drive with the engine management light on?
Often you can drive carefully to a garage if the light is steady and the car drives normally, but get it diagnosed soon. If it flashes, or the car runs roughly or loses power, slow down, stop safely and get help.
Why did a warning light come on and then go off?
Lights come on briefly when you start the engine as a self-check. If one comes on while you are driving and then goes off, get it checked anyway: an intermittent fault is still a fault.
Will a warning light fail my MOT?
It can. The MOT checks the lights for airbags, ABS, stability control, the electronic parking brake, brake fluid and power steering, and tyre pressure monitoring on newer cars.
Where can I find out what a symbol means?
In your owner's handbook, which shows every warning light for your car. If you do not have a paper copy, the manufacturer's website usually has one.
Sources
Facts last checked against these pages on .
- The Highway Code, Annex 6: Vehicle maintenance, safety and security(opens in a new tab)
- GOV.UK: Car parts checked at an MOT(opens in a new tab)
General information for drivers in Great Britain, not legal advice. Northern Ireland has different MOT rules. Spotted a mistake? Email hello@carfixnearme.com. See how we write and check our advice.
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