What do the different colours of dashboard warning lights mean?

Red lights indicate a serious fault — pull over and stop driving when safe to do so. Amber/yellow lights are advisories — there's a fault, but you can usually drive to a garage. Green and blue lights are simply information — they tell you that a system (headlights, indicator, cruise control) is active. The colour-coding is standardised across almost all car makes.

Can I drive with the engine management light on?

Sometimes — but only briefly, and only if the light is steady amber. A flashing amber engine management light, or a red light of any kind, means stop. A steady amber light could be something minor like a loose fuel cap, or something serious like a misfire that's damaging your catalytic converter. Either way, get it diagnosed within days, not weeks.

How much does it cost to fix a dashboard warning light?

It varies enormously. A loose fuel cap fixing the engine light costs £0. A new battery for a charging light is £80–£250. A failed catalytic converter is £400–£1,500. A failed turbo is £1,000–£2,500. The light only tells you the system involved — only diagnosis can tell you the cause and cost.

Why does my warning light come on and then go off?

Intermittent lights usually point to an intermittent fault — a connector that loses contact when the car is cold, a sensor that misreads briefly, or a system that resets itself after the fault clears. The fault code is logged even when the light goes off, so a garage with a diagnostic tool can still see what triggered it. Don't assume a light that's gone away has fixed itself.

Can a garage clear a warning light without fixing the problem?

Yes, and unfortunately some do. A diagnostic tool can clear any fault code temporarily — but if the underlying issue isn't fixed, the light will return within a few drive cycles. If you've paid for a 'repair' and the light is back within a week, the work wasn't done. Insist on seeing the replaced parts and ask for a printout of the fault codes before and after.

Dashboard Warning Lights Explained — What They Mean and What They Cost

The first warning light is the worst. You're driving along, everything's normal, and suddenly a symbol you've never seen before lights up. Your first instinct — is this expensive, or can I keep driving?

This guide explains the colour-coding system every car uses, walks through the 12 lights you're actually likely to see, and gives you the typical UK repair cost range for each. Because knowing roughly what you might be looking at is the difference between a calm trip to the garage and panic.

How colour tells you the urgency

Every dashboard symbol uses one of three colour bands. Once you know what each colour means, you can react appropriately even for a symbol you've never seen before.

Red — stop as soon as it's safe. A red light indicates a serious fault that could damage the car or put you in danger. The two most common are the brake system light and the engine oil pressure light. Continuing to drive can turn a £200 repair into a £4,000 one.

Amber or yellow — drive carefully to a garage. A fault has been detected, but the car can usually still be driven. The system may go into "limp mode" — reduced power, top speed limited — to protect itself. Get it checked within days.

Green or blue — informational only. These confirm a system is active: headlights on, indicator flashing, cruise control engaged. No action needed.

A useful rule: if you're not sure what a light means, look at the colour first. That alone tells you whether to pull over now or finish your journey and book a garage visit.

The 12 lights you're most likely to see

1. Engine management light (amber)

The check-engine light. Indicates the engine control unit has detected something it doesn't like. Steady amber: drive carefully, book a diagnostic — could be anything from a loose fuel cap (£0) to a failed catalytic converter (£400–£1,500). Flashing amber: stop driving — a misfire is dumping unburnt fuel into the catalytic converter and destroying it as you drive.

Typical fix cost: £80 diagnostic, then anywhere from £0 to £2,000 depending on the cause.

2. Brake system warning (red)

A red exclamation mark inside a circle, or the word "BRAKE." Means one of: handbrake is still on, brake fluid is dangerously low, or there's a brake system fault. Check the handbrake first. If that's fully released and the light stays on, do not drive — your brakes may fail.

Typical fix cost: low brake fluid (£40 top-up + leak find), worn pads triggering sensor (£90–£350 — see our brake pads guide).

3. Battery / charging warning (red)

A red battery symbol. Means the battery is not being charged while the engine is running — almost always a failed alternator or a snapped alternator belt. The car will run on the battery alone until the battery dies, typically 20–60 minutes. Get to a garage immediately.

Typical fix cost: alternator belt £80–£150; alternator replacement £200–£600.

4. Engine oil pressure (red)

A red oil-can symbol. The most dangerous warning light. Stop the engine immediately — driving even one mile can destroy the engine. Low oil pressure means insufficient lubrication; metal-on-metal contact will follow within seconds at higher revs.

Typical fix cost: low oil level (£20 top-up); failed oil pump £500–£1,200; engine rebuild £2,500+.

5. Coolant temperature (red)

A red thermometer over wavy lines. The engine is overheating. Pull over and stop the engine immediately. Continuing risks a cracked cylinder head — a £1,000–£3,000 repair. After 20 minutes of cooling, top up coolant if low and limp to a garage.

Typical fix cost: low coolant £30–£60; failed thermostat £150–£300; head gasket failure £1,200–£3,000.

6. DPF / diesel particulate filter (amber)

A small filter symbol with dots. Diesel cars only. The filter has too much soot. Try a 20-minute run at sustained 50+mph first to trigger regeneration. If the light stays on or goes red, head to a garage.

Typical fix cost: forced regen £80–£150; full cleaning £150–£500; replacement £1,000–£3,500 (see our DPF cleaning guide).

7. ABS warning (amber)

The letters "ABS" in a circle. Means the anti-lock braking system has detected a fault. Your normal brakes still work, but ABS won't activate in an emergency stop — you can lock the wheels. Get it diagnosed within a week.

Typical fix cost: wheel speed sensor £80–£200; ABS module £400–£900.

8. Airbag / SRS (amber)

A person symbol with a circle in front of them. Means the airbag system has a fault — your airbags may not deploy in a crash. Always get checked promptly; airbags are non-negotiable safety equipment.

Typical fix cost: seatbelt buckle sensor £80–£150; clock spring £150–£400; ECU fault £200–£600.

9. Tyre pressure (TPMS) (amber)

An exclamation mark inside a horseshoe. Either a tyre is low on pressure, or the TPMS sensor itself has failed. Check pressures first with a gauge or at a forecourt — that solves it 80% of the time.

Typical fix cost: nail in tyre £15–£30 repair; new TPMS sensor £40–£120; sensor reset on new tyres £20–£40.

10. Glow plug (amber, diesel only)

A coiled-wire symbol. On a cold start, this is normal — wait for it to go out before cranking. If it stays on while driving, or comes on at random, one or more glow plugs has failed.

Typical fix cost: glow plug replacement £80–£250 depending on engine access; glow plug control module £200–£400.

11. Power steering (amber or red)

A steering-wheel symbol, sometimes with an exclamation mark. Means the power assistance has failed or is failing. The car will still steer but with much more effort — especially at low speeds. On hydraulic systems, often a low fluid level. On electric systems, a fault code is logged.

Typical fix cost: power steering fluid top-up £40; electric power steering motor £400–£1,200.

12. Stop-start warning (amber)

A capital "A" with a circular arrow. Means the stop-start system isn't engaging — usually because the battery has weakened or temperature is wrong. Often the first sign your battery is on the way out.

Typical fix cost: new battery £80–£250 (see our battery guide); battery sensor £50–£120.

When to ignore the light, when not to

You can never truly ignore a warning light — but the response varies massively by colour:

Red lights: pull over within minutes. Engine, brakes, coolant — these don't tolerate delay.
Flashing amber lights: same urgency as red. Common on misfire warnings.
Steady amber lights: drive carefully to a garage within days. The car is asking for attention but isn't in danger.
Green/blue lights: confirm a system is on. No action.

The most expensive mistake drivers make is ignoring an amber light because the car still seems to drive fine. Most amber lights mean the car has reduced its own output to protect itself — by the time you've ignored it for weeks, the damage is done.

Get a diagnostic before getting a quote

If you walk into a garage with a vague "the light's on" — you can't get a proper quote. Most garages will charge £40–£80 for a diagnostic scan that reads the exact fault code. Get the code before agreeing to any repair. That code tells you exactly what's wrong, and lets you compare quotes from multiple garages on the same job.

Reputable garages will give you the code in writing along with the recommended fix. If a garage refuses to share the diagnostic code — go elsewhere.

How to spot a garage that's overcharging you — protecting yourself once you have the diagnosis.
DPF cleaning cost guide — for the diesel particulate filter light.
Brake pads replacement guide — for the brake wear warning.
Car battery replacement guide — for the stop-start and battery warnings.
All UK car repair cost guides — see what every common repair should cost.