Does ABS Light Appearing Lead to MOT Failure?

Dashboard warning lights can be worrying at the best of times – especially when your MOT is just around the corner.

Not only do they give you limited time to investigate and resolve the issue, but they could also result in a potential  MOT failure and an unexpected bill.

An ABS warning light showing on your dashboard is no exception. If it’s appearing, you might be wondering: will this cause my car to fail its MOT?

In this guide, we’ll answer that question and more – including what ABS is, why the warning light may be on, and how to fix it before test day.
 

What are Anti-Lock Brakes?

Anti-lock braking systems (ABS) are a safety feature designed to prevent your wheels from locking up under heavy braking.

Instead of the wheels skidding, ABS rapidly applies and releases braking pressure – typically up to 15 times per second – helping your tyres maintain grip on the road.

This controlled braking allows you to steer while slowing down, reducing the risk of skidding or losing control, especially in slippery conditions.

ABS has been mandatory on all new vehicles in the UK since 2004, making it a core part of your car’s safety system.
 

Why Is My ABS Light Showing?

When your car starts up, it briefly illuminates several dashboard warning lights – including the ABS – as part of a system check.

If the ABS light stays on or appears while driving, it’s a signal that something may be wrong with the system.
There are a few common reasons your ABS light may appear:

• Low brake fluid: Hydraulic pressure is essential for ABS to function – if brake fluid levels are too low, it can trigger the warning light.
• Faulty wheel speed sensors: These sensors monitor the speed of each wheel. A failure in one or more can disrupt ABS function.
• Control module issues: This unit processes signals from the sensors and adjusts braking accordingly. Corrosion or electrical faults here can cause the warning light.
• Worn ABS pump: If the hydraulic pump responsible for modulating brake pressure is failing, ABS may shut down entirely.

In most cases, the ABS system disables itself when a fault is detected, switching control back to your standard braking system.

While your car may still be drivable, it won’t have the added protection that ABS offers in emergencies.
 

Will I Fail My MOT If My ABS Light Is Showing?

Yes – if your ABS warning light is permanently on at the time of your MOT, your car will more than likely fail the test.

Since ABS is a legally required safety feature on cars registered after 2004, any fault that affects its operation is classed as a Major defect under MOT guidelines.

This applies even if your car’s regular braking system feels fine. MOT testers are not assessing how the car drives – they’re checking whether essential safety systems are working, and a persistent ABS light indicates a fault that needs fixing before a pass certificate can be issued.
 

ABS Light Appearing: Quick Fixes

Fixing an ABS warning light depends on the cause, but here are a few possible solutions your garage might recommend:

• Top up brake fluid: If levels are low, a quick refill might resolve the warning – but be sure to have the system checked for leaks.
• Replace faulty sensors: Diagnostic tools can quickly identify if a wheel speed sensor has failed, allowing for a straightforward replacement.
• Repair the ABS module: Corroded or damaged control modules may require cleaning, rewiring, or complete replacement.
• Pump replacement: If the ABS pump is worn out, this component may need to be replaced or rebuilt.

Most repairs will require diagnostics using a scan tool to read fault codes stored in the car’s ECU (Engine Control Unit). These codes help pinpoint the issue and save time (and cost) during the repair process.

If your MOT is approaching, it’s worth booking a diagnostic check in advance – especially if your dashboard lights are active.

Final Thoughts

An ABS warning light might not stop your car from driving – but it can stop your car from passing its MOT.

As one of the most critical safety systems fitted to modern vehicles, ABS needs to be in full working order for your car to be deemed road-legal.

Whether the fix is as simple as topping up brake fluid or as complex as replacing a module, it’s always best to act early.

Ignoring the warning light not only risks MOT failure but could also compromise your safety on the road.

By addressing the issue promptly, you’ll give your car the best chance of passing its test – and keep your braking system performing as it should.