Use the Motor Vehicle Expert Warning Light Checker
Use the diagnostic app to check common dashboard warning lights, possible causes, safe-to-drive advice, MOT implications and sensible next checks before replacing parts.
Warning light meaning
Check engine, battery, oil, coolant, ABS, airbag, brake and tyre pressure warnings.
Safe to drive?
Get simple guidance on whether to stop, drive carefully or arrange inspection.
MOT impact
Understand whether the warning light may affect an MOT test.
Next checks
See sensible checks before replacing parts or clearing codes.
Quick answer
Red warning lights usually mean stop safely and deal with the issue urgently. Amber warning lights usually mean a fault has been detected and should be checked soon. Green or blue lights are normally information lights showing that a system is switched on.
Do not judge a dashboard warning light by colour alone. A flashing light, warning light with smoke, overheating, brake changes, steering changes, power loss or rough running should be treated more seriously.
What warning light colours mean
Red warning lights
Red usually means urgent. Stop safely if the warning relates to oil pressure, brakes, overheating, steering, charging or if the car feels unsafe.
Amber warning lights
Amber usually means a fault has been detected. The car may still drive, but diagnosis should not be delayed.
Green or blue lights
Green or blue lights are usually informational, such as dipped beam, main beam, indicators or active systems.
A flashing warning light is often more urgent than a steady light. For example, a flashing engine management light can suggest a misfire that may damage the catalytic converter.
Most common car warning lights explained
Engine management light
Indicates an engine, emissions, fuel, ignition, sensor or exhaust-related fault.
Engine light guide →Oil pressure light
Low oil pressure can damage the engine quickly. Stop safely and check the issue.
Oil warning guide →Battery light
Usually points to a charging system fault, alternator issue, belt problem or poor electrical connection.
Battery warning guide →Brake warning light
Can relate to low brake fluid, handbrake faults, brake wear or a braking system problem.
Brake warning guide →Coolant warning light
May mean low coolant, overheating, a leak, fan issue, thermostat problem or cooling system fault.
Coolant warning guide →ABS warning light
Means the ABS system has detected a fault. Normal braking may remain, but ABS assistance may not work.
ABS warning guide →Airbag warning light
Can mean a fault with the airbag or restraint system and may affect MOT results.
Airbag warning guide →Tyre pressure light
Usually means low tyre pressure, pressure imbalance or a TPMS sensor issue.
TPMS reset guide →Traction control light
Can mean the system is active, switched off, or has detected a traction or stability fault.
Traction control guide →DPF warning light
Diesel particulate filter warnings can point to soot build-up, failed regeneration or limp mode risk.
DPF warning guide →Red dashboard warning lights: usually urgent
Red lights normally need faster attention because they can involve safety or expensive damage. Some red lights mean stop immediately; others mean check the system before continuing.
- !Oil pressure light: stop safely because low oil pressure can damage the engine quickly.
- !Brake warning light: do not ignore braking system warnings, especially with soft pedal feel or low fluid.
- !Coolant temperature light: stop if the engine is overheating or steam appears.
- !Battery charging light: the car may lose electrical power if the alternator is not charging.
- !Power steering light: steering assistance may be reduced or unavailable.
- !Airbag warning: restraint system faults can affect safety and MOT results.
Amber dashboard warning lights: check soon
Amber lights usually mean the car has detected a fault or a system needs attention. The car may still drive normally, but the fault should not be left until it becomes worse.
Engine management
Can involve emissions, sensors, misfires, fuel or exhaust faults.
ABS or traction control
The car may brake normally, but extra safety assistance may be reduced.
Tyre pressure
Check pressures and inspect for punctures, cuts or uneven tyre wear.
DPF warning
Diesel filter problems can get worse if ignored, especially with short journeys.
Glow plug warning
On diesels, this may relate to starting, emissions or engine management faults.
Service warning
May be routine maintenance or a reminder linked to mileage and time.
Can you keep driving with a warning light on?
Usually stop
Stop safely for oil pressure warnings, brake warnings, overheating, heavy smoke, strong fuel smells, severe steering faults or flashing engine lights with misfire.
Drive carefully only if safe
Some amber lights may allow careful driving if the car feels normal, but the fault should still be checked.
Book diagnosis soon
Engine, ABS, airbag, DPF, TPMS and traction warnings should not be left until they become worse or fail an MOT.
Use the app first
The diagnostic app can help you check severity, safe-to-drive guidance and likely next checks.
Open diagnostic app →Warning lights and MOT tests
Some dashboard warning lights can cause MOT problems if they indicate faults with monitored safety or emissions systems.
Engine management light
Can affect MOT where emissions or engine faults are present.
Read MOT guide →Airbag light
Airbag warning lights can fail because they relate to occupant safety.
Read airbag MOT guide →Tyre pressure light
TPMS warnings can affect MOT results on vehicles where the system is required.
Read TPMS MOT guide →Traction control light
Stability and traction control faults may affect MOT outcome.
Read traction MOT guide →Common MOT failures
Lights, brakes, tyres, suspension, emissions and visibility problems.
MOT failure guide →What to check next
1. Note the exact symbol
Different manufacturers use slightly different symbols, so check the handbook if you are unsure.
2. Check the colour
Red and flashing lights normally need faster attention than steady amber lights.
3. Watch how the car behaves
Power loss, smoke, overheating, braking changes, steering changes or rough running make the warning more serious.
4. Scan fault codes
Fault codes can identify the system involved, but they still need proper interpretation.
5. Avoid guessing parts
Do not replace random parts just because a warning light is on. Confirm the cause first.
6. Fix before MOT
Do not leave safety, emissions, ABS, airbag or TPMS warnings until test day.
Common mistakes drivers make
- !Clearing a warning light without diagnosing the cause.
- !Ignoring a warning because the car still drives normally.
- !Waiting until MOT day to fix an ABS, airbag, engine or TPMS warning.
- !Driving with oil pressure, overheating or brake warnings showing.
- !Replacing sensors without checking wiring, fluid levels or related faults.
- !Assuming every dashboard light means an expensive repair.
Best mechanic-style advice
Start with the basics: identify the symbol, check the colour, notice whether it is flashing or steady, and pay attention to how the car feels. A warning light with smoke, overheating, poor braking, heavy steering, power loss or rough running is much more serious than a light on its own.
Do not keep clearing codes and hoping the warning stays off. A stored fault code is a clue, not the whole diagnosis. The right repair depends on confirming the cause.
Related warning light and diagnostic guides
Frequently asked questions
What is the most serious warning light?
Oil pressure, brake, overheating, charging and steering warnings are among the most serious because they can affect safety or cause damage quickly.
Can I ignore a warning light?
No. Even minor warnings can become serious if ignored. At minimum, identify the symbol and check whether the vehicle feels different.
Why did my warning light come on suddenly?
It could be a sensor fault, electrical issue, worn component, fluid level problem or sudden mechanical fault.
Can a warning light go off by itself?
Sometimes a light may disappear if the fault is intermittent, but stored fault codes may remain and the problem can return.
Should I clear a warning light with a scanner?
Only clearing the light without fixing the cause is not a proper repair. The warning may come back and the underlying fault may still be present.
Can dashboard warning lights fail an MOT?
Yes. Engine management, ABS, airbag, TPMS, brake and stability control warnings can affect the MOT depending on the fault and vehicle system.
What does a flashing warning light mean?
A flashing warning light often means the system is actively warning of a more urgent condition. A flashing engine light, for example, can indicate a misfire risk.
What should I check first?
Check the symbol, colour, whether it is flashing, fluid levels where safe, tyre pressures, warning messages and how the car drives.