Tyres  /  Tyre News /  Help and Advice  / How a Worn Shock Absorber Can Lead to MOT Failure

Noticed a strange knocking sound or excessive bounce when driving?

With your MOT coming up, these could be signs your shock absorbers are worn – and they might just be the reason your car fails its test.

While shock absorbers are often overlooked during routine maintenance, they’re critical for keeping your car stable and safe.

And if they’re in poor condition, they can trigger a major defect during an MOT – meaning no pass certificate until they’re fixed.

In this guide, we’ll explain what shock absorbers do, how they’re assessed during an MOT, and what signs might signal a problem before test day.
 

What Is a Shock Absorber?

Shock absorbers are part of your car’s suspension system that works alongside springs to control the movement of the wheels and chassis.

When you drive over bumps or potholes, the springs compress to absorb the impact. Shock absorbers then dampen this movement, stopping your car from bouncing excessively. They also help keep your tyres firmly in contact with the road, improving grip, braking, and steering.

If your shock absorbers are worn, your car may feel unstable, dip forward under braking, or bounce more than usual after a bump. Not only does this affect comfort – it can seriously impact safety.
 

Can a Shock Absorber Fail My MOT?

Yes – and depending on the severity, a faulty shock absorber can lead to a major defect or even dangerous MOT defect.
According to GOV.UK’s MOT guidelines, testers will check for:

• Negligible damping: If the shock absorber has little or no damping effect, it will result in a Major defect.
• Severe leakage: A leaking shock absorber might not always lead to a fail – but if the leak is significant enough to impair function, it will.
• Loose or damaged components: Shock absorbers that are insecurely mounted, likely to detach, or heavily damaged will trigger a Major or Dangerous fail.
• Excessive bush wear: Worn bushes (the rubber mounts that connect shock absorbers to the suspension) can also result in a fail.

What If My Shock Absorber Is Leaking?

A thin film of fluid on the shock absorber isn’t necessarily a fail. MOT testers are instructed not to reject the part if the leak is minor and doesn’t affect performance.

But if you’ve spotted fluid under your car or the component is visibly coated, it could be a sign of serious wear – and may lead to a failed test.

A leaking shock absorber MOT failure will occur if the leak is heavy enough to affect the component’s function.

A shock absorber leaking MOT fail outcome depends on whether the damping is compromised, not just the presence of fluid.
 

Shock Absorber Dust Cover MOT Failure

The dust cover (also known as a gaiter) is a protective sleeve that shields the shock absorber’s piston rod from dirt, debris, and moisture.

While a missing or torn dust cover might not directly cause an MOT failure, it’s still a concern.

A damaged dust cover allows contaminants into the shock absorber, leading to accelerated wear, corrosion, and fluid leaks – which, if bad enough, will cause an MOT fail.

So, while shock absorber dust cover MOT failure isn’t listed as a standalone reason to fail, it often leads to other defects that are.
 

Quick Fixes Before MOT Test Day

If your MOT is approaching and you suspect an issue with your shock absorbers, here are a few things to check – or have your garage inspect:

• Bounce test: Push down firmly on each corner of your car. If it bounces more than once or twice before settling, the shock absorber may be worn.
• Check for leaks: Look around the shock absorber for oil residue or puddles. Heavy fluid loss is a red flag.
• Inspect mounting bolts: Loose or rusted bolts can make the unit insecure – which is an MOT fail.
• Look at the dust cover: If it’s cracked or missing, it won’t fail the MOT on its own – but it’s worth replacing to protect the component.
• Listen for noises: Clunking or knocking when driving over bumps often points to suspension wear.

If you're unsure, book a pre-MOT inspection or ask for a suspension check. Most garages can carry out a quick assessment and let you know whether a part needs replacing before your MOT date.

Final Thoughts

Your shock absorbers play a vital role in keeping your car stable, responsive, and safe.

But when they’re worn, leaking, or no longer damping effectively, they become a liability – and could cause your car to fail its MOT.

Catching the signs early – like bouncing, leaks, or knocking noises – can help you fix the problem before test day. By doing so, you’ll improve your chances of passing the MOT the first time around.

Don’t ignore the warning signs – check your suspension, book a diagnostic if needed, and give your car the best shot at a clean MOT pass.