MOT advisory explained
“Shock absorbers has a reduced damping effect”
The one shock absorber advisory that is about how the car behaves, not how the part looks. It is a judgement by the tester, it usually applies to both sides, and it is the closest an MOT gets to telling you the dampers are worn out.
A shock absorber’s job is to stop the spring bouncing. The tester judged that one or more of yours is doing that job less well than it should, though it still has enough effect to pass.
6.8% of these fail on the same shock absorber at the next test. That understates the point. Tired dampers lengthen braking distances and wear tyres long before they become an MOT failure, so the cost of waiting is paid elsewhere.
Fitted at an independent garage. Dampers are never replaced singly. If the top mounts are aged, changing them at the same time adds £40–£90 and saves paying the labour twice.
Do not confuse this with “light misting of oil”. Misting describes a shock that looks slightly wet and may work perfectly. This wording describes one that may look fine and does not work properly.
A “shock absorbers has a reduced damping effect” advisory means the tester judged that one or more shock absorbers control the car’s bounce less well than they should, but not so badly as to fail. The fix is a new pair on that axle, costing £150–£360 fitted at an independent garage. According to DVSA MOT data analysed by PriceMyRepair, 6.8% of 252,845 such advisories failed on the same shock absorber at the next test.
An advisory based on behaviour
No machine measures it. An MOT bay has no equipment for testing dampers. The tester forms a view from how the car settles as it is driven in, how it reacts on the brake rollers, and how the body moves when a corner is pressed down. It is an experienced opinion, and that is why it is an advisory far more often than a fail.
What worn damping feels like. The car carries on moving after a bump when it should settle at once. The nose dips hard under braking. On a motorway it floats, and in a crosswind it wanders. None of it arrives suddenly, so most drivers adapt and stop noticing.
What it does to the rest of the car. A wheel that is not held firmly on the road brakes less well and wears its tyre in patches. The usual clue is a tyre with a scalloped, uneven tread on the same axle. If you have that and this advisory together, the dampers are the cause.
Will it fail next year?
This wording has been used 821,279 times. For 252,845 of them the same vehicle’s next MOT is on record.
| What happened at the next test | Share |
|---|---|
| Failed on the same component | 6.8% |
| Same advisory recorded again | 13.8% |
According to DVSA MOT data analysed by PriceMyRepair: 252,845 advisories followed to the same vehicle’s next test. Rows can overlap.
The failure rate sits between the other shock absorber advisories: above casing damage at 4.3%, below a worn mounting bush at 8.9%. What stands out is the last column. Only 13.8% are advised again a year later, the lowest of the group.
There are two ways to read that. Some owners act on it, because the advisory confirms what they already felt in the way the car drives. And because it is a matter of judgement, a different tester the following year may simply not raise it.
| Advisory wording | Fails on same part | Advised again | Followed |
|---|---|---|---|
| Anti-roll bar linkage ball joint has slight play | 10.0% | 17.1% | 2,098,185 |
| Shock absorbers has a slightly worn bush | 8.9% | 19.9% | 607,181 |
| Shock absorbers has light misting of oil | 7.9% | 26.2% | 5,360,491 |
| Suspension arm pin or bush worn | 7.4% | 29.3% | 8,344,577 |
| Shock absorbers has a reduced damping effect | 6.8% | 13.8% | 252,845 |
| Coil spring corroded | 5.0% | 39.1% | 4,780,118 |
| Shock absorbers has slight external damage to the casing | 4.3% | 23.2% | 452,485 |
Dampers wear with mileage, and mileage comes with age. The advisory is almost absent on new cars, 0.2 per 1,000 tests at 3–4 years, and twenty times as common by 20 years and over. The chance of failing next time creeps up with it, from 5.0% to a peak of 7.5% at 13–15 years.
| Age of car | Per 1,000 tests | Fails on same part | Followed |
|---|---|---|---|
| 3–4 years | 0.2 | 5.0% | 5,785 |
| 5–6 years | 0.6 | 5.5% | 14,871 |
| 7–9 years | 1.3 | 6.4% | 44,894 |
| 10–12 years | 2.2 | 7.0% | 59,606 |
| 13–15 years | 3.1 | 7.5% | 60,348 |
| 16–19 years | 4.0 | 7.2% | 45,718 |
| 20 years and over | 4.2 | 5.8% | 18,494 |
At 1.7 per 1,000 tests this is a rare line, far rarer than worn dampers are on the road. With no equipment to measure damping, testers only write it when the effect is obvious.
So if it is on your certificate, the wear was plain enough for someone to notice without instruments. Take it as a firmer signal than its wording suggests.
The reverse also holds. A clean MOT says nothing about the state of your dampers. On a car past eighty thousand miles on its original shocks, they are likely to be worn whether or not anyone has written it down.
Exact wording on your certificate
The fail version swaps one word. Reduced damping is an advisory. Negligible damping, meaning the shock has effectively stopped working, is a fail.
| Line on the certificate | Result | Code |
|---|---|---|
| Shock absorbers has a reduced damping effect | Advisory — pass | 5.3.2 (d) |
| Shock absorber has a reduced damping effect | Advisory — pass | 5.3.2 (b) |
| Shock absorber has negligible damping effect | Major — fail | 5.3.2 (d) |
The worn bush and casing damage advisories are concentrated at the rear. This one is spread evenly over all four corners, and the most common tester notes are “both” and “both sides”. Dampers on an axle wear together, and testers record it that way.
| Position written by the tester | Share of all instances |
|---|---|
| Nearside front | 20% |
| Offside rear | 20% |
| Nearside rear | 20% |
| Offside front | 19% |
| Rear | 10% |
| Front | 8% |
From 821,279 recorded instances. Testers can add their own note after the standard wording. The most common on this advisory: “both” (36,514), “both sides” (23,322), “both side” (5,581), “both rear” (5,120), “both front” (4,178), “nearside and offside” (3,070), “all” (2,842), “both rears” (1,600).
What new dampers cost
| Job | Price fitted | Notes |
|---|---|---|
| Pair of shock absorbers, one axle | £150–£360 | Always as a pair |
| Top mounts, added to the job | £40–£90 | Optional, sensible on an older car |
| Alignment afterwards | £40–£60 | After front struts |
Independent garage prices with parts and labour. Cars with electronically adjustable dampers cost considerably more, so check which yours has before comparing quotes. Model-by-model prices are on the shock absorber replacement cost page.
Can I still drive with this advisory?
It is legal and it passed. Leave more distance in the wet, where worn dampers cost the most braking grip, and take extra care when the car is loaded or towing. Have the shocks replaced within a few months. This is one advisory where the MOT is not the deadline that matters.
Enter your reg for the full MOT record. Look for tyre wear advisories on the same axle in earlier years. Together with this line they tell the whole story.
Which cars get this advisory most?
These are the models where testers write this advisory most often, against an all-vehicle rate of 1.7 per 1,000 tests.
| Model | Per 1,000 tests | Vs all cars | Tests |
|---|---|---|---|
| Volkswagen Caddy | 7 | 4.1× | 1,459,681 |
| Kia Sorento | 7 | 4.0× | 392,464 |
| Mercedes-Benz Sprinter | 7 | 3.8× | 2,101,182 |
| Renault Kangoo | 6 | 3.4× | 700,467 |
| BMW 120 | 6 | 3.3× | 466,460 |
| Land Rover Freelander | 5 | 2.7× | 1,480,990 |
| BMW 3 Series | 4 | 2.6× | 4,399,110 |
| BMW 116 | 4 | 2.6× | 1,102,596 |
| Volkswagen Crafter | 4 | 2.6× | 585,956 |
| BMW 1 Series | 4 | 2.5× | 710,378 |
Model families are grouped by the first word of the DVSA model name, so “Transit” covers every Transit variant. Only models with at least 60,000 tests are ranked.
Working vehicles lead: the Volkswagen Caddy at 4.1 times the average, with the Mercedes-Benz Sprinter, Renault Kangoo and Volkswagen Crafter also present. Vans carry loads, and loaded dampers wear faster.
The other pattern is BMW. Four of the ten entries are 1 Series and 3 Series variants, which DVSA records under several model names. We can report that they are there. The data does not say why.
What to do next
- Ask which axle. The certificate may not say. The tester will know, and it halves the possible bill.
- Look at the tyres on that axle. Run a hand over the tread. If it feels scalloped, high and low in patches, the dampers have been worn for some time.
- Price the pair, with and without top mounts. On a car over ten years old the mounts are usually worth doing in the same visit.
- Check what type of damper you have. Standard dampers are an everyday job. Adaptive or air systems are not, and the quote should say which it covers.
Reduced damping effect advisory FAQ
What does shock absorbers has a reduced damping effect mean?
The tester judged that one or more shock absorbers are not controlling the car’s bounce as well as they should. They still work well enough to pass, so it is recorded as an advisory.
How does an MOT tester check damping?
By observation. There is no damper-testing equipment in an MOT. The tester judges how the car settles and how it behaves on the brake rollers. The advisory is written only when the effect is obvious.
Will reduced damping fail my next MOT?
It may. According to DVSA MOT data analysed by PriceMyRepair, 6.8% of 252,845 such advisories failed on the same shock absorber at the next test. The fail wording is “negligible damping effect”.
How much does it cost to replace worn shock absorbers?
A pair of shock absorbers costs £150–£360 per axle fitted at an independent garage, and new top mounts add £40–£90. These are estimates and final quotes come from garages.
Is it safe to drive with reduced damping?
It is legal, and the car passed. Braking distances are longer and handling is less stable, most of all in the wet or with a load. Replace the shocks within a few months and do not wait for the next test.
Do both shock absorbers need replacing?
Yes. Shock absorbers are replaced as a pair on the same axle so the car behaves the same on both sides. Testers most often record this advisory against both sides anyway.
How these figures were calculated. According to DVSA MOT data analysed by PriceMyRepair, from the DVSA anonymised MOT test results (Open Government Licence v3.0): 350,943,111 tests. This advisory was recorded 821,279 times; 252,845 of those were followed to the same vehicle’s next test between 180 and 730 days later. “Fails on the same part” means a failure at that next test under the same defect code and naming the same component, on either side of the vehicle. Testers do not always name a component the same way twice, so the figure is a floor. Method and how to cite.