Dashboard Warning Lights Explained: Which Ones Mean Stop

Written by Petro Olekhnovych, mobile mechanic in Aylesham, Kent

Dashboard warning lights use a traffic light system. A red light means a possibly serious fault, so stop as soon as it is safe and get help. An amber light means the car needs checking soon, and green, white or blue lights are just information.

Symbols vary between makes, so your handbook is the final word for your car. Below are the lights that matter most, grouped by how urgent they are.

What the colours of dashboard warning lights mean

National Highways and the RAC both describe the same basic system:

• Red: there may be a serious fault. The RAC says to stop driving as soon as it is safe and call for recovery. National Highways says not to start a journey with a red light showing.
• Amber (yellow): the car needs maintenance or checking. National Highways also advises not to start a journey with an amber light on.
• Green, white or blue: a system is switched on or working, such as headlights or cruise control. No need to stop.

It is normal for many lights to come on briefly when you turn the ignition on. National Highways says that if any stay on after the engine starts, get advice before setting off.

Red lights: stop as soon as it is safe

These are the lights to take seriously straight away.

Oil pressure (oil can symbol). This can mean low oil level or low oil pressure. The RAC says to stop as soon as safely possible and switch off the engine. Read more in our guide to the oil pressure warning light.

Engine temperature (thermometer in liquid). The engine is overheating. The RAC says to stop straight away and wait for it to cool before checking the coolant. Our post on the engine temperature warning light explains the common causes.

Brake system (circle with an exclamation mark). This can point to a braking problem such as low brake fluid, though on some cars the same light also shows when the handbrake is on. If the handbrake is off and the light stays on, the RAC says pull over as soon as it is safe.

Battery or charging. The RAC says this may mean the battery is not charging or there is a fault, and that you should not drive with it on.

Power steering (red). The RAC says it is not advisable to drive with the red power steering light on.

Airbag. The RAC says not to drive with the red airbag light on, because part of the system may not work in a crash.

A flashing engine management light

The engine management light is usually amber, but a flashing one is more serious. The AA says it means a more serious problem than a steady light and should be checked immediately. If the light is flashing, pull over safely and switch off. See our full guide to the engine management light.

Amber lights: get it checked soon

Steady engine management light. The AA says this usually means a less serious issue, often to do with emissions. You can usually continue your journey if the car drives normally, but get it checked soon.

ABS. The RAC says the ABS light means a fault has been detected. On its own, the RAC says it is safe to continue your journey with extra caution. If the ABS light comes on together with the red brake light, stop straight away.

Tyre pressure. The RAC says to stop as soon as it is safe and check your tyre pressures.

Low coolant. The RAC says you should not drive with insufficient coolant. Let the engine cool, then check the level.

DPF (diesel particulate filter). The RAC says to get it checked at a garage as soon as you can.

Which warning lights fail an MOT?

The DVSA’s MOT inspection manual lists several warning lights as defects. These are all major faults, which means an MOT fail:

• Engine management light (MIL) on or not working, petrol and diesel
• ABS warning light showing a fault, or not working
• Airbag (SRS) warning light showing a fault
• Electronic power steering warning light showing a fault
• Electronic parking brake warning light showing a fault
• Tyre pressure monitoring system faulty, on cars first used from 1 January 2012

A lit brake fluid warning light is listed as a minor defect. A lit brake pad wear indicator on its own is not a reason for failure, although the tester will still check the pads.

If a light is on before your MOT, get it looked at first. Our pre-MOT check covers this and other common fail points.

What to do if a warning light comes on while driving

1. Do not panic or brake hard. Check the colour and whether it is flashing.
2. If it is red or flashing, find a safe place to stop. National Highways says not to stop in a live lane unless absolutely necessary. On a motorway, try to reach the next junction or services, or use an emergency area, layby or the hard shoulder.
3. Switch off and check your handbook for that exact symbol.
4. Call for recovery if a red light stays on. Do not drive on with oil pressure, temperature or brake warnings.
5. For an amber light, book a check soon and note any other symptoms, such as noises, smells or a change in how the car drives.

A warning light tells you a system has spotted a problem. It does not always tell you which part has failed. That is where fault finding comes in.

How we can help

We do warning light diagnostics and fault finding at your home or workplace. We read the fault codes, find the cause and tell you what it needs before any work starts. We are based in Aylesham and cover Canterbury, Dover, Deal, Sandwich, Folkestone and the surrounding villages.

Our labour is £30-£50 per hour depending on the job and how difficult it is. Parts are extra, and the price is agreed on WhatsApp first. If a red light means the car should not be driven, do not drive it to us. We come to you.

Frequently asked questions

Can I drive with a warning light on?
It depends on the colour. Stop for red or flashing lights. With a steady amber light you can usually drive carefully, but get it checked soon.

Why did a light come on and then go off?
The system may have spotted a fault that came and went. It is still worth having the car checked, so the cause can be found before it gets worse.

Will clearing the code fix the problem?
No. Clearing a code only turns the light off. If the fault is still there, the light will come back.
Need help? Send a WhatsApp to 07563 350335 with your car’s make and model and we’ll come to you.

Sources

• RAC: Dashboard warning lights guide
• National Highways: Dashboard warning lights, what you need to know
• The AA: Why is my engine management light on?
• GOV.UK: MOT inspection manual, section 1 Brakes
• GOV.UK: MOT inspection manual, section 2 Steering
• GOV.UK: MOT inspection manual, section 5 Axles, wheels, tyres and suspension
• GOV.UK: MOT inspection manual, section 7 Other equipment
• GOV.UK: MOT inspection manual, section 8 Nuisance