Car dashboard warning lights: what every UK driver needs to know
A warning light on your dashboard can be confusing or alarming. This guide explains what each colour means, which lights require you to stop immediately, and which you can safely drive on to a garage.
Warning light colours: the three-colour rule
UK car manufacturers follow a traffic-light colour system for dashboard warnings. Knowing what each colour means lets you make the right call instantly.
Red
Stop immediately
A serious fault that risks damage to the car or danger to you. Pull over safely and turn off the engine. Do not continue driving.
Amber / Orange
Attention soon
A fault that needs investigation but is not an immediate emergency. You can usually drive carefully to a garage, but do not ignore it.
Green / Blue
Information only
Confirmations that a system is active: indicators, headlights, cruise control. No action needed unless the light is unexpected.
Red warning lights: stop immediately
Oil pressure
Symbol: Oil can with drop
Engine oil pressure is critically low. Stop and turn off the engine immediately. Driving further can seize the engine completely within minutes.
What to do: Stop now. Check oil level. Do not restart without investigation.
Engine temperature
Symbol: Thermometer in waves
Engine is overheating. Coolant leak, thermostat, or water pump failure are common causes.
What to do: Stop safely, turn off engine. Wait 15+ minutes before checking coolant. Do not open radiator cap when hot.
Battery / charging
Symbol: Red battery outline
The alternator has stopped charging. Battery will drain and car will cut out.
What to do: Turn off non-essential electrics. Drive directly to a garage or stop.
Brake warning
Symbol: Circle with (!) in parentheses
If the handbrake is off: brake fluid may be low or brake circuit has failed. If handbrake is applied: this is normal and the light will go off once you release it.
What to do: Check handbrake first. If released and light stays on, stop and call for assistance. Do not drive on low brake fluid.
Amber warning lights: attention soon
Engine management (EML)
Symbol: Engine outline
The ECU has detected a fault in the engine or emissions system. Could be minor (loose fuel cap) or significant (sensor failure, misfire).
What to do: Steady light: book a diagnostic check soon. Flashing light: reduce speed, avoid high revs, book urgently to protect the catalytic converter.
ABS
Symbol: ABS letters in a circle
Anti-lock braking system fault. Normal brakes still work but ABS will not activate.
What to do: Drive carefully to a garage. Leave larger stopping distances.
Airbag / SRS
Symbol: Person in seat with circle
Airbag system fault. Airbags may not deploy correctly in an accident.
What to do: Book a diagnostic check promptly.
Power steering
Symbol: Steering wheel with exclamation
Electric or hydraulic power steering fault. Steering will become heavy, especially at low speeds.
What to do: Drive carefully to a garage. Expect heavier steering input at parking speeds.
Traction control / ESP
Symbol: Car with wavy lines
Steady: system has activated temporarily on a slippery surface (normal). Constant: system fault.
What to do: Steady light that goes off: normal. Constant light: book a diagnostic check.
DPF (diesel only)
Symbol: Dotted pipe shape
Diesel particulate filter is clogged. Common in cars used mainly for short trips.
What to do: Try a 20-minute motorway run at 60 mph+ in a lower gear to trigger regeneration. If light remains on, book a mechanic.
AdBlue (diesel only)
Symbol: Exhaust pipe with drop
AdBlue level is low. Modern Euro 6 diesel engines require AdBlue to control NOx emissions.
What to do: Top up AdBlue fluid. Many filling stations sell it. The car may refuse to start once AdBlue runs out completely.
Tyre pressure (TPMS)
Symbol: Tyre cross-section with (!)
One or more tyres is significantly under-inflated.
What to do: Check all four tyre pressures and inflate to the levels in your manual or door sill sticker. If light persists, a TPMS sensor or slow puncture may be the cause.
Coolant level
Symbol: Thermometer with wavy line
Coolant level is low in the reservoir.
What to do: Let engine cool completely, then top up with the correct coolant. Check for leaks. If it keeps dropping, book a mechanic.
Service due
Symbol: Spanner or 'SERVICE'
The car has reached its scheduled service interval based on mileage or time.
What to do: Book your service. Delaying too long can invalidate warranty and cause accelerated engine wear.
Green and blue lights: information only
Turn signals
Symbol: Flashing arrows
Indicators are active. Normal operation.
What to do: No action needed.
Sidelights / headlights on
Symbol: Sun or half-sun
Lights are switched on. Normal operation.
What to do: No action needed.
Cruise control
Symbol: Speedometer with arrow
Cruise control is active.
What to do: No action needed.
Need a garage for a warning light check?
Post your job on AutoFixFair and get real quotes from local garages and mobile mechanics. Diagnostic checks typically cost £40 to £90. See prices before you commit.
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Frequently asked questions
What does a red warning light mean on my dashboard?
A red warning light means a serious fault that requires immediate attention. The most critical are oil pressure (stop immediately and turn off the engine), engine temperature (overheating: stop and let it cool), and brake warning when the handbrake is not applied. If you see a red light and are unsure, pull over safely, turn off the engine, and call for assistance. Do not continue driving.
What does an amber or orange warning light mean?
Amber or orange warning lights indicate a fault that needs attention soon but is not an immediate emergency. Common examples are the engine management light, ABS warning, airbag warning, and DPF (diesel particulate filter) light. You can usually continue driving to a garage, but you should book a diagnostic check promptly. Ignoring amber lights can allow small faults to become expensive ones.
What does the engine warning light (check engine) mean?
The engine management light (EML) is an orange or amber symbol that looks like an engine outline. It means your car's ECU has detected a fault in the engine or emissions system. The fault could be anything from a loose petrol cap to a faulty oxygen sensor or catalytic converter issue. You should book a diagnostic check to read the fault codes. If the light flashes, ease off the throttle and book in urgently as a misfire can damage the catalytic converter.
Can I drive with the engine warning light on?
If the engine management light is on but steady (not flashing), you can usually drive carefully to a local garage to have the fault codes read. Avoid high-speed motorway driving and heavy acceleration. If the light is flashing, reduce speed immediately, avoid high revs, and get it checked as soon as possible to prevent catalytic converter damage. If you also see red warning lights or notice unusual smells or sounds, stop and call for assistance.
What is the oil pressure warning light and why is it serious?
The oil pressure warning light is a red oil can symbol. It means the engine oil pressure has dropped critically low. This is one of the most serious warning lights: if you continue driving, the engine can seize within minutes and require complete replacement. Stop the car immediately, turn off the engine, and check the oil level. If the oil level is normal and the light stays on, do not restart the engine. Call for roadside assistance.
What does the ABS warning light mean?
The ABS (anti-lock braking system) warning light is an amber light, usually showing the letters ABS inside a circle. It means the ABS system has a fault and will not activate during emergency braking. Your normal brakes still work, so you can drive to a garage, but leave much larger stopping distances as ABS will not prevent wheel lock-up. Get it diagnosed promptly, especially in wet or icy conditions.
What does the DPF warning light mean on a diesel car?
The DPF (diesel particulate filter) warning light means the filter is becoming clogged with soot. Diesel cars need regular motorway-speed runs to burn off accumulated soot through a process called active regeneration. If you mainly do short, low-speed journeys, the DPF cannot clear itself. You can try a 20-minute motorway run at 60 mph or above in a lower gear to trigger regeneration. If the light remains on, book a mechanic as a blocked DPF may need a forced regeneration or replacement.
What does the battery or charging warning light mean?
The battery warning light (a red battery symbol) means your car is not charging properly. The most common cause is a failing alternator, but it can also be a broken drive belt or battery terminal issue. This is a red light: if the alternator has stopped charging, your battery will drain and the car will eventually cut out, sometimes mid-journey. Turn off non-essential electrical loads (heated rear window, air con, radio) and drive directly to a garage or stop if the car begins to feel sluggish.
What does the temperature warning light mean?
The engine temperature warning light (a red thermometer in waves) means the engine is overheating. This is critical: stop the car as soon as it is safe to do so, turn off the engine, and do not open the bonnet immediately (pressurised coolant can cause burns). Wait at least 15 minutes for the engine to cool. Check the coolant level in the reservoir (never open the radiator cap when hot). Common causes include a coolant leak, a faulty thermostat, or a failed water pump. Call for assistance rather than continuing to drive.
Why is my tyre pressure warning light on?
The TPMS (tyre pressure monitoring system) light is an amber symbol showing a cross-section of a tyre with an exclamation mark. It means one or more tyres have pressure significantly below the recommended level. Check and inflate all four tyres to the pressures shown in your car's manual or door sill sticker. The light should go off once pressures are correct. If it stays on after correcting pressures, there may be a TPMS sensor fault or a slow puncture.
What does the airbag or SRS warning light mean?
The airbag or SRS (supplemental restraint system) warning light is an amber symbol showing a person in a seat with a circle in front. It means the airbag system has a fault. In the event of an accident, the airbags may not deploy correctly, which is a significant safety concern. You can drive the car to a garage, but you should do so promptly. This is not a fault to ignore or defer for months.
How much does it cost to diagnose a warning light?
A diagnostic check to read fault codes typically costs between £40 and £90 at an independent garage. Main dealerships often charge more. Many garages will put the diagnostic fee toward the repair cost if you proceed with them. AutoFixFair lets you post your job and compare diagnostic quotes from local garages and mobile mechanics so you can see real prices before you commit.