Dashboard warning lights can range from the trivial — a door not fully closed — to the immediately dangerous — a brake system failure or red engine overheating warning. Understanding what each warning light means, how urgently you need to act, and what you should and should not do when a warning appears is essential knowledge for every driver in 2026. Ignoring a warning light can be costly, dangerous or both.
Understanding Warning Light Colours
Red Warning Lights — Act Immediately
Red warning lights indicate a serious problem that requires immediate attention. If a red light appears, stop the car safely as soon as possible and address the issue before continuing:
- Do not continue driving unless you are certain the issue is benign
- If in doubt, pull over, stop and call for assistance
- Red lights can indicate issues that risk your safety or cause significant engine damage
Amber Warning Lights — Act Soon
Amber or yellow warning lights indicate a problem that should be investigated but which does not require immediate stopping. You should address the issue at the next convenient opportunity — within days, not weeks:
- The issue may worsen if ignored
- It may be safe to continue driving but have the system checked
- Check the owner's manual for specific guidance on each amber light
Green and Blue Lights — Information Only
Green and blue indicator lights are informational — they confirm a system is active or functioning normally. The blue headlight main beam indicator and green sidelight and indicators are examples. No action is required for these.
Critical Red Warning Lights
Engine Temperature Warning (Thermometer Symbol)
The red engine temperature warning — a thermometer in a bowl of waves — indicates the engine is overheating. Pull over immediately, switch off the engine and allow it to cool. Check coolant levels only when the engine has cooled sufficiently to open the coolant expansion tank cap safely. Do not open the cap while the engine is hot — the coolant is under pressure and can cause severe burns.
Oil Pressure Warning (Oil Can Symbol)
The red oil can warning indicates critically low oil pressure. Stop the engine immediately. Do not continue driving under any circumstances — driving with no oil pressure causes catastrophic engine damage within seconds. Check oil level on the dipstick. If oil is low, add oil to the correct level. If oil is present and the light remains on, call for recovery.
Brake System Warning (Exclamation Mark in Circle)
The brake warning light indicates a problem with the brake system. If the light is on with the handbrake applied, the handbrake is on or not fully released. If the light is on with the handbrake released:
- Brake fluid level may be low — check the brake fluid reservoir
- There may be a fault in the ABS system
- The electronic brake force distribution system may have failed
Do not drive if the brake pedal feels different from normal — reduced assistance, excessive travel or pulling to one side.
Power Steering Warning (Steering Wheel with Exclamation)
A red power steering warning indicates a failure in the power steering system. The car can still be steered manually but the effort required will be significantly higher. Drive slowly and carefully to the nearest garage or call for assistance.
Airbag Warning (Person with Deploying Airbag)
The airbag warning light indicates a fault in the supplementary restraint system. While the car can still be driven, the airbags may not deploy in an accident. Have the system checked immediately.
Common Amber Warning Lights
Check Engine Light (MIL — Malfunction Indicator Lamp)
The check engine light — an engine block silhouette — indicates a problem with the engine management system. The car can usually be driven, but performance may be reduced and fuel consumption may increase. Common causes include:
- Loose fuel cap — try tightening before anything else
- Oxygen sensor failure
- Mass airflow sensor fault
- catalytic converter problems
- Ignition system faults
Have the fault codes read using an OBD scanner — available from GBP 10 for basic units — to identify the specific issue.
DPF Warning Light (Filter Symbol)
The DPF warning light — a rectangular filter symbol — indicates the Diesel Particulate Filter is becoming blocked. Drive at motorway speeds for 20-30 minutes to allow active regeneration to clear the filter. If the light persists, consult a garage.
Tyre Pressure Warning (Exclamation Mark in U-shape)
The tyre pressure monitoring system has detected a tyre with significantly lower pressure than the others. Check all tyre pressures and inflate to the recommended level. If the tyre appears flat or the warning persists after inflation, inspect the tyre for damage or puncture.
ABS Warning (ABS in Circle)
The ABS warning light indicates a fault in the Anti-lock Braking System. Normal braking function should remain — only ABS assistance is lost. Have the system checked at the next service opportunity.
Battery/Charging Warning (Battery Symbol)
The battery warning light indicates the charging system is not functioning — the alternator is not charging the battery. This is an electrical fault that will eventually drain the battery and leave you stranded. Drive to the nearest garage immediately while the battery still has charge. If the battery was flat when you started the car, do not switch off the engine.
What to Do When a Warning Light Appears
- Assess the colour — red means stop immediately, amber means act soon
- Check the owner's manual if available — it explains each specific light for your vehicle
- Do not ignore any warning light, even if the car seems to be driving normally
- Use an OBD scanner to read fault codes for engine management lights
- Seek professional diagnosis for any warning that persists or recurs