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Tyres  /  Tyre NewsHelp and Advice  / What Dashboard Lights Can Fail My MOT?

What Dashboard Lights Can Fail My MOT?

What Dashboard Lights Can Fail My MOT?

Dashboard warning lights are designed to protect you – not punish you.

But when test day comes around, they can become the deciding factor between a smooth MOT pass and a frustrating failure.

Whether it’s a simple sensor glitch or a sign of something more serious, an illuminated light on your dash could indicate a problem that needs urgent attention that can cause your vehicle to fail its MOT test.

In this guide, we’ll explain which dashboard lights will fail your MOT, which ones won’t (but could lead to trouble down the road), and how to stay ahead of them before your appointment.
 

Can a Car Fail Its MOT Due to a Dashboard Warning Light?

Yes – certain dashboard lights can and will fail your MOT.

Modern vehicles are fitted with built-in warning systems to detect faults in key components such as the braking system, airbags, and engine.

During an MOT, if these systems report a fault by displaying a persistent warning light, the car is considered unroadworthy until the issue is resolved.

But not all warning lights are treated equally. MOT testers follow DVSA guidelines, and the outcome depends on what the warning light refers to and how critical it is to the safety or emissions of the vehicle.
 

Which Dashboard Lights Are an Automatic MOT Fail?

Here are some key warning lights that will result in an MOT fail if illuminated during the test:
 

1. ABS Warning Light (Anti-lock Braking System)

If your ABS light is on, the system designed to prevent wheel lock-up during braking isn’t working correctly. This is a major safety concern, and any fault in the ABS system leads to an immediate MOT failure.

Even though your brakes may still function, without ABS you lose critical control in emergency braking situations – especially in wet or icy conditions.

ABS dashboard symbol

2. Airbag Warning Light (Supplementary Restraint System - SRS)

A lit airbag light indicates a fault with your vehicle’s airbag system – a key safety feature. If this system isn't functioning, airbags may not deploy in a crash, increasing the risk of injury. This is also classified as a major defect, and will automatically fail the test.

Airbag warning light dashboard symbol

3. Engine Management Light (EML) – Red or Persistent Amber

The engine management light suggests a fault within your engine or emissions system, such as a misfire, faulty sensor, or exhaust problem.

  • Red EML: A serious fault and always an MOT fail.
  • Amber EML: If steady and not flashing, it might not automatically fail depending on the vehicle and fault code – but most testers will still fail the car unless evidence proves it's benign.

In any case, it’s safer to address any illuminated EML before the test.

Engine management light dashboard symbol

Other Dashboard Lights That Can Affect Your MOT

Some warning lights may or may not directly cause a fail – but they signal faults that more than likely will if not repaired in time. These include:
 

4. Brake System Warning Light

This may indicate low brake fluid, worn pads, or a hydraulic fault. While not always an instant fail based on the light alone, if the underlying issue is serious (e.g. insufficient braking performance), the vehicle will fail.

Brake system warning dashboard symbol

5. Electronic Parking Brake Light

A fault in the electronic parking brake system, if active during the test, will be noted. If the parking brake can’t be operated safely, this becomes a fail.

Electronic Parking Brake dashboard symbol

6. Coolant Temperature Warning Light

Indicates that your engine is overheating — often due to low coolant, a faulty thermostat, or a broken water pump. If the tester finds that overheating is likely to affect engine operation or emissions, your vehicle could fail.

Coolant Temperature Warning dashboard symbol

7. Battery or Charging System Light

This signals a charging issue or alternator fault. On its own, it may not fail the test, but if the battery condition prevents proper operation of lighting, steering, or other safety systems, it becomes a defect.

Battery or Charging System dashboard symbol

Warning Light Colour Meanings (Red vs Amber vs Green)

Understanding your dashboard light colours helps identify how urgent the issue is – and how it might affect your MOT:

  • Red Lights: Critical faults. Stop driving immediately. These almost always result in an MOT failure.
  • Amber/Orange Lights: Important but less urgent. Usually indicate degraded function, not complete failure. May not result in an automatic fail, but can if linked to emissions or safety.
  • Green/Blue Lights: Information only. For example, full beam headlights or cruise control active. These won’t cause a fail.

How to Clear Dashboard Warning Lights Before Your MOT

Here are a few quick checks and fixes that can prevent dashboard lights from ruining your MOT:

  • Scan for Fault Codes: Ask your garage to run a diagnostic scan. This reveals the exact reason for the light and confirms whether it's serious.
  • Top Up Fluids: Low oil, coolant, or brake fluid can trigger warnings. Make sure all levels are correct.
  • Check Battery Health: An ageing battery can cause random light triggers. Replace it if it’s struggling to hold charge.
  • Reset TPMS (Tyre Pressure Monitoring System): After topping up tyres, don’t forget to reset the system. An unresolved TPMS light won’t fail the MOT but may mask real pressure problems.
  • Don't Ignore the Light: A quick dashboard bulb check before your MOT can highlight issues. Addressing these early reduces your chance of a fail.

Final Thoughts

Dashboard lights are your car’s way of speaking up – and during an MOT, the tester is listening too.

From ABS faults to engine management warnings, some lights will instantly prevent your car from passing. Others might hint at deeper issues that need tackling before they escalate.

By learning what each light means and responding early, you can avoid a failed MOT and potentially save on repair costs in the long run.

If you see a warning light before your MOT is due, don’t wait.

Book a diagnostic check through Blackcircles.com, fix any issues, and give your vehicle the best chance of passing its MOT!

Buy new tyres at Blackcircles.com
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