UK Authority Hub · Updated 2026

Dashboard Warning Lights: Complete UK Guide

Every dashboard warning light explained for UK drivers — what it means, whether to stop immediately, common causes, UK repair costs, and whether it affects your MOT.

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Stop immediately

🚨 Stop Immediately — Emergency Warnings

These require pulling over safely without delay. Continued driving risks serious damage or safety failure.

🛢️

Engine Oil Pressure

Stop immediately. Risk of catastrophic engine damage.

Full guide

🌡️

Engine Overheating

Stop safely. Continued driving risks head gasket failure.

Full guide

🔋

Battery / Charging

Drive carefully to garage. You have limited time.

Full guide

🫧

Brake System

Stop carefully. Check brake fluid. Do not drive further.

Full guide

⚠️

Engine Management (Flashing)

Stop. Active misfiring destroys catalytic converter.

Full guide

Caution & advisory

🟡 Caution & Advisory Warnings

Not immediate emergencies, but require investigation and booking within days — not weeks.

⚠️

Check Engine (Steady)

Stored fault code. Book diagnostic soon.

🔧

Service Due

Scheduled maintenance reminder.

🔵

Tyre Pressure (TPMS)

One or more tyres significantly under-inflated.

🛑

Brake Pad Wear

Pads near minimum — replace within days.

🔄

Start-Stop Fault

Auto start-stop system disabled or faulty.

Full directory

All Warning Lights — Full Directory

Every dashboard warning light covered on MotR with a full explanation, repair costs, and MOT guidance.

Engine Oil Warning

Battery Warning

Check Engine / EML

Service Light

Glow Plug (Diesel)

TPMS / Tyre Pressure

Automatic Gearbox

Hybrid System

Start-Stop System

Electric Power Steering

Brake Pad Warning

ABS Warning

Airbag Warning

DPF Warning (Diesel)

Coolant Temperature

EPC Warning (VW Group)

AdBlue Warning

Oil Pressure Warning

Traction Control

Power Steering Warning

CAUTION

MOT relevance

Warning Lights & Your MOT

Automatic MOT Failure

Any dashboard warning light that is illuminated at the time of the MOT test is an automatic failure. This has been the case since the 2018 MOT reforms. The tester does not need to diagnose the underlying fault — the presence of any lit warning is sufficient to fail the test. Resolve all warning lights before booking any MOT.

At a glance

Warning Light Severity at a Glance

Warning Light	Colour	Severity	Can You Drive?	MOT Risk	Action
Engine Oil Pressure	🔴 Red	STOP	No — stop immediately	Auto-fail	Pull over, turn off engine
Engine Overheating	🔴 Red	STOP	No — stop safely	Auto-fail	Stop, let engine cool
Brake System	🔴 Red	STOP	No — check fluid first	Auto-fail	Check fluid, call garage
Engine Management (flashing)	🟡 Amber	STOP	No — active misfire	Auto-fail	Stop, prevent cat damage
Battery / Charging	🔴 Red	CAUTION	Limited — drive to garage	Auto-fail	Drive directly to garage
Engine Management (steady)	🟡 Amber	CAUTION	Yes — with care	Auto-fail	Book diagnostic scan
ABS Warning	🟡 Amber	CAUTION	Yes — brakes still work	Auto-fail	Book garage promptly
Airbag / SRS	🟡 Amber	CAUTION	Yes — airbags inactive	Auto-fail	Book garage — safety risk
Tyre Pressure (TPMS)	🟡 Amber	CAUTION	Yes — check pressures	Auto-fail	Check & inflate tyres
Brake Pad Warning	🟡 Amber	ADVISORY	Yes — briefly	Auto-fail	Replace pads within days
Service Due	🔵 Blue/Amber	ADVISORY	Yes	Auto-fail if lit at test	Book service within weeks
AdBlue (diesel)	🟡 Amber	ADVISORY	Yes — until empty	Auto-fail	Top up AdBlue fluid

Any illuminated warning light at the time of MOT test is an automatic failure under the 2018 DVSA test rules. Resolve all warnings before booking.

Questions & answers

Frequently Asked Questions

What is the most serious dashboard warning light?

The oil pressure warning light (red oil can) is arguably the most critical — it requires immediate stopping as continued driving causes engine damage within minutes. Engine overheating and brake system failures are equally serious. Any red warning light should be treated as a stop-immediately situation.

Can a dashboard warning light fail an MOT?

Yes. Any illuminated warning light on the dashboard at the time of the MOT test causes an automatic failure. This was formalised in the 2018 MOT test changes. The tester does not need to diagnose the fault — a lit warning light alone is sufficient for a failure.

What is the difference between red and amber warning lights?

Red warning lights require immediate action — typically stop the vehicle safely as soon as possible. Amber/yellow warning lights indicate a fault requiring investigation but are generally not immediately dangerous. Blue and green lights are informational. Not all manufacturers follow this convention exactly, so always check your specific vehicle handbook.

Can I clear a warning light by disconnecting the battery?

Disconnecting the battery will clear stored fault codes from the ECU's short-term memory. However, the codes will return if the underlying fault is still present — typically within 1–3 drive cycles. Clearing codes to mask a fault before an MOT is not legal and will result in incomplete ECU readiness monitors, which some testers flag.

What should I do if multiple warning lights come on at once?

Multiple simultaneous warning lights often indicate an electrical supply fault (low battery, alternator failure) rather than multiple independent faults. The electrical system affects all warning systems simultaneously. Start by checking battery and alternator voltage before assuming multiple separate faults.

How much does it cost to get dashboard warning lights diagnosed?

A diagnostic scan at a garage typically costs £40–£80 for reading and interpreting OBD fault codes. An OBD-II reader for home use costs £15–£50. Many automotive parts retailers (Halfords, Euro Car Parts) offer free code reading with a walk-in visit.

What does a flashing warning light mean compared to a steady one?

A flashing or blinking warning light always indicates greater urgency than a steady version of the same light. A flashing engine management light, for example, indicates an active misfire that can destroy the catalytic converter within minutes. A steady engine management light means a stored fault that should be investigated soon but is not an immediate emergency. Always treat a flashing light as a stop-immediately signal.

Can I drive with more than one warning light on at the same time?

It depends on which lights are illuminated. If any red warning light is on, do not drive. If only amber or blue advisory lights are on, you may be able to drive carefully to a garage — but get an OBD diagnostic scan as soon as possible. Multiple amber lights simultaneously often point to a single electrical fault rather than multiple independent problems.

How long does a dashboard warning light diagnostic take?

A basic OBD-II scan to read fault codes takes 5–10 minutes. A full diagnostic investigation to identify the root cause of the fault, test components, and confirm a repair takes 30–60 minutes at a garage. If you just want to know what codes are stored, many fast-fit retailers offer free code reading while you wait.

Is it safe to drive with the service due light on?

The service light (spanner or oil service indicator) is an advisory-level warning — it does not indicate an immediate safety risk. However, ignoring it increases the risk of engine wear, especially if oil change intervals are exceeded. Book a service within 1–2 weeks of the light appearing. If you are unsure whether it is a service reminder or an oil pressure/low oil level warning, check your vehicle handbook immediately.

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Warning-light guidance is general UK advice. Any illuminated warning light at the time of the MOT test is an automatic failure under the 2018 DVSA test rules. MotR is not affiliated with DVLA, DVSA or any vehicle manufacturer. Last reviewed 14 June 2026.