Do Dashboard Warning Lights Cause an MOT Failure?

When preparing your car for its MOT, one question many UK drivers have is: Do dashboard warning lights cause an MOT failure? With modern vehicles featuring an increasing number of electronic systems, dashboard lights have become more important than ever in determining a vehicle’s roadworthiness.

What Are Dashboard Warning Lights?

Dashboard warning lights are indicators designed to alert drivers about potential issues with their vehicle. These lights cover a range of systems, from brakes and airbags to engine management and emissions. Some are advisory, while others signify critical faults.

Can Dashboard Warning Lights Fail Your MOT?

Yes, certain dashboard warning lights can indeed cause an MOT failure. According to UK MOT testing standards, any illuminated warning light related to safety or emissions can result in a fail. The most common culprits include:

• Airbag warning lights – If this light is on, it indicates a potential fault with the airbag system, which is considered a major safety concern.
• ABS (Anti-lock Braking System) lights – A malfunctioning ABS can compromise braking performance.
• Brake system warning lights – Critical for safety, this will result in an immediate fail if illuminated.
• Engine management or emissions lights (MIL) – If the light is on, it may indicate higher emissions than legally allowed.

Advisory vs. Major Faults

Not all lights mean an automatic fail. Some dashboard lights may trigger advisories, allowing you to pass the MOT but warning you to fix the issue soon. However, lights related to braking, airbags, or emissions usually count as major faults and will need immediate attention.

How to Prevent MOT Failure Due to Warning Lights

1. Perform a pre-MOT check – Turn on your ignition and look for any illuminated lights on your dashboard.
2. Use a diagnostic tool – Many garages or auto centres can quickly read error codes and reset lights if the problem is minor.
3. Address issues early – Do not wait until the MOT test day. If a warning light has been on for weeks, have it inspected promptly.

What If a Light Comes On Just Before the MOT?

If a warning light appears just before your MOT, it’s best to delay the test if possible and have the issue diagnosed. A simple reset may solve the problem if it’s a temporary fault, but ongoing issues must be properly repaired.

Final Thoughts

So, do dashboard warning lights cause an MOT failure? In many cases, yes—particularly when they relate to key safety or emissions systems. Regular maintenance, prompt attention to illuminated lights, and a pre-MOT check can save you from unnecessary failures and repair costs.