The little rubber boot that keeps grease in and grit out of a suspension or steering ball joint has split. The joint itself may still be tight today, which is why this is often Minor — but once the boot is open, road grit and water get in and the joint's life is measured in months, not years.
Wording as it commonly appears on an MOT certificate: “Ball joint dust cover damaged or deteriorated so it no longer prevents the ingress of dirt”.
What does it mean?
The little rubber boot that keeps grease in and grit out of a suspension or steering ball joint has split. The joint itself may still be tight today, which is why this is often Minor — but once the boot is open, road grit and water get in and the joint's life is measured in months, not years.
How serious is it?
Usually recorded as: Minor, Major. The tester assesses the actual vehicle on the day, so your certificate is what counts.
What normally causes it?
- Age and ozone cracking of the rubber
- Grit blasted up from the road cutting through the folds
- Damage during previous work, often from a joint splitter
- A joint that has been over-greased and burst its own boot
What a mechanic would check
I look for grease flung around the inside of the wheel arch, then squeeze the boot to see if it's split or just dirty. If it's open I check the joint itself for play straight away, because a boot that's been gone a while usually means the joint is already on the way out.
What might need replacing
- A replacement boot kit where the joint is still good and serviceable
- A ball joint
- A complete lower arm on cars where the joint isn't sold separately
- A wheel alignment afterwards
Can you still drive it?
A split boot on a tight joint is safe to drive on while you get it sorted. If the joint has play as well, that's a different story — treat it as urgent.
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This is general guidance from a UK mechanic, not a substitute for a physical inspection. Only the tester who inspected your vehicle can confirm what was recorded and why.