Suspension advisories at the MOT by car age: worn bushes, corroded springs and leaking shock absorbers

The short answer

Suspension advisories are rare on young cars and routine on old ones. In class 4 tests carried out between 2021 and 2025, a worn suspension pin or bush was noted as an advisory on 7.1% of first tests on cars aged 10 to 14, about 1 in 14 (44,980,002 tests). On cars aged 3 to 5 the same note appeared on 0.9% of tests, and the most common suspension advisory at that age was a shock absorber leaking fluid. Corrosion is the item that changes most with age: a corroded and weakened coil spring was noted on 0.1% of tests at 3 to 5 and on 7.3% at 15 and over.

An advisory is not a fail. It is the tester telling you a part is on its way, and on the suspension that usually means a bush, a spring or a damper that will be a fail at a later test if left. The point of reading the list now, before the salt season, is that corrosion is the one process you can slow down.

What the data shows

Each cell is the share of all first tests in that age band on which the item was recorded as an advisory; a dash means the item was not among the twelve most recorded advisories for that band. The wear items, pins, bushes and ball joints, rise steadily with age. The corrosion items, springs, sub-frames and arms, start from almost nothing and then climb fastest after about ten years. The shock absorber row is the exception: it is the most common suspension note on a young car and then levels off, which fits a part that leaks when it is a few years old and is usually replaced rather than left.

Advisories become fails. The most recorded suspension fail in the same tests was a coil spring fractured or broken, on 0.3% of tests at 3 to 5, 2.0% at 6 to 9, 4.1% at 10 to 14 and 3.4% at 15 and over. The corroded spring on the advisory list and the broken spring on the fail list are the same part a year or two apart.

Why the salt season matters for the suspension

The MOT inspection manual's suspension section says in plain words why: thin-gauge pressings with box sections, which is what suspension arms and sub-frames are, can collect road dirt, salt or other chemicals that cause severe local corrosion. Grit goes down, spray carries it into every seam under the car, and it sits there until something washes it out. Springs rust where they sit in their seats; arms rust from the inside of their box sections; the welded sub-frame rusts where it collects the mud.

The manual also draws the line the tester draws. Slight seepage leaving a film of fluid on a shock absorber is not a reason for rejection, which is why so many young cars carry it as an advisory rather than a fail. A damper showing signs of severe leakage, or a suspension component excessively damaged or corroded, is a major defect. A component fractured or likely to fail is dangerous. Corrosion within 30cm of a spring or suspension mounting, which the manual calls a prescribed area, is judged on whether it significantly reduces the strength of the structure.

What to look at before winter

1. The advisory history. Run the registration through the free GOV.UK MOT history service and read every test, not just the last. A bush or a spring noted two years running is a part that has been left; a corrosion note that has moved from advisory wording to a fail is the pattern in the table above.
2. Springs, by torch. With the car on level ground, look at each coil spring where it sits in its lower seat. Flaking, pitting and a seat full of wet grit are what the tester sees. A spring that has snapped at the bottom coil often shows as the car sitting lower on one corner, or a clonk over bumps.
3. Dampers. A dry dusty film is normal. Wet oil running down the body of the damper, or an oily patch on the inside of the wheel, is the fail-side wording in the manual.
4. Bushes and joints. Knocks over small bumps, a steering wheel that shimmies on uneven surfaces, or uneven tyre wear across one tyre are the everyday signs. The tester checks these with the wheel loaded and levered; you can only hear and feel them.
5. Wash the underside. A rinse of the arches and underbody after a run on gritted roads is the one maintenance step that targets the corrosion items in this table directly. Do it when the roads are dry again, not in a frost, and let the car dry before it sits.
6. Fix the advisory, not the fail. A corroded spring replaced as a pair is routine work; a snapped spring on a motorway is not. The table shows the advisory arrives first.

What this does not mean

These figures describe how a national fleet of cars tested, not how any one car will. They say what was recorded, not why: use, roads, climate, storage and maintenance all decide how fast a suspension ages, and a well-kept fifteen-year-old car can carry none of these notes while a neglected six-year-old carries several. The shares are per item, so a car with two notes appears in two rows, and the rows do not add up to a share of cars with any suspension advisory. No make or model is named here; the age pattern is the point, and it holds across the fleet.

Sources and method

Each table cell is the share of class 4 first tests in the age band, 2021-2025, on which the named item was recorded as an advisory, across the whole national fleet. Band bases (first tests): aged 3-5, 33,793,352; aged 6-9, 50,103,915; aged 10-14, 44,980,002; aged 15 and over, 31,405,150. Vehicle age is test year minus first-used year. The store records some items under two reasons-for-rejection with identical wording (worn pins and bushes; shock absorber fluid leak); the larger row is shown and the twins are not added. A dash means the item was not among the twelve most recorded advisories for that band. The fail figures for a fractured or broken coil spring come from the same tests, as a share of first tests in each band. Shares are per item; a test can record several. MOT inspection manual wording as read on 6 November 2026.

• DVSA anonymised MOT results, class 4 first tests, 2021-2025
• GOV.UK: MOT inspection manual, section 5, axles, wheels, tyres and suspension
• GOV.UK: Check the MOT history of a vehicle

This article is general information drawn from published test records. It is not professional, mechanical or legal advice, and an MOT pass or a clean MOT history does not guarantee that a car is roadworthy today. If you are unsure about a car, have it inspected by a qualified mechanic. You can check any vehicle's MOT history free on the official GOV.UK MOT history service.