MOT advisory “Sound deadening material not fully secure” — meaning and what to do
Last updated · OBDCode UK editorial
In plain English: the tester noted a noise, emissions or leaks item that was not a fail on that MOT. Monitor to next MOT.
Can you drive with this?
Drive with care. This advisory alone does not normally mean you must stop driving. Still plan the repair before the next MOT so it does not become a fail.
12V electrical safety. On a 12V battery: disconnect negative first, reconnect negative last. Prevent sparks and short circuits. Stop if the battery is damaged or sits near orange high-voltage cables.
What the tester saw
MOT testers work from the DVSA inspection manual. For this item the manual wording is “Any part of the noise suppression system insecure”. In plain English: the tester judged that wear or deterioration on the sound deadening material had not gone far enough to reject at that test. That is why it was recorded as an advisory rather than a failure. It is not a statement about the vehicle’s condition or legal status today.
If it worsens to the manual fail wording above, DVSA would class that defect as Major. That grade describes the fail threshold, not the recorded advisory.
Do you need to fix it?
An advisory did not affect that test’s result. It is the tester telling you what is likely to need attention, and how soon depends on the item.
- Monitor to next MOT. Loose sound-deadening material can wait for the next service if it is not near hot exhaust parts or fouling moving components. Book sooner if you smell burning, see material hanging under the car, or hear it dragging.
- Can you DIY? Basic external checks may be suitable for a careful DIY driver with household tools, on firm level ground. We do not publish strip-down or fitting steps here.
- Buying a used car? Repeated advisories for the same item across several years of MOT history mean the owner has been ignoring it. Check the car’s full record with our free MOT history check.
What happened to other cars with this advisory
These figures are a statistical association from the national MOT extracts. They are not a prediction about this car, and we have not inspected it.
Their rate of failing a 2025 MOT for any reason was 23.9% (95% CI 22.2–25.7), against 18.2% (95% CI 18.2–18.2) for cars that passed without this advisory.
The median car in this cohort was 10.0 years old with 68,203 miles at the 2024 test.
By age at the 2024 test
Scroll horizontally to read every age column.
| Age | Cars | Same-item fail | Not tested again |
|---|---|---|---|
| 5–8 years | 632 | 0% (95% CI 0.0–0.6) | 2.1% (95% CI 1.2–3.5) |
| 8–12 years | 486 | 0.82% (95% CI 0.3–2.1) | 4.1% (95% CI 2.7–6.3) |
| 12–16 years | 714 | 0.98% (95% CI 0.5–2.0) | 8.0% (95% CI 6.2–10.2) |
By mileage at the 2024 test
Scroll horizontally to read every mileage column.
| Mileage | Cars | Same-item fail | Not tested again |
|---|---|---|---|
| Under 40,000 miles | 473 | 0% (95% CI 0.0–0.8) | 1.9% (95% CI 1.0–3.6) |
| 40,000–80,000 miles | 850 | 0.71% (95% CI 0.3–1.5) | 2.9% (95% CI 2.0–4.3) |
| 80,000–120,000 miles | 556 | 0.90% (95% CI 0.4–2.1) | 9.5% (95% CI 7.4–12.3) |
| 120,000 miles and over | 377 | 0.80% (95% CI 0.3–2.3) | 18.8% (95% CI 15.2–23.1) |
Models with the highest same-item fail rate
Among models with enough cars in this cohort (at least 200 each), these had the highest rate of failing on the same item in 2025. Showing 1 qualifying models.
Scroll horizontally to read every model column.
| # | Make and model | Cars | Same-item fail | Not tested again |
|---|---|---|---|---|
| 1 | Volkswagen Golf | 1,010 | 0.50% (95% CI 0.2–1.2) | 3.9% (95% CI 2.8–5.2) |
A robustness re-run on the 1,082 cars tested in January–June 2024 only — so the next annual test almost always falls inside 2025 — found a same-item fail rate of 0.37% (95% CI 0.1–0.9) and a not-retested gap of +0.2 points. A December 2024 test may not be due until 2026, which can make a car look as if it vanished; the first-half window removes most of that censoring.
Of the 953 cars that failed on this line in 2024, 0.73% (95% CI 0.4–1.5) failed on it again in 2025 — 289 times the rate for cars that did not fail on this item, and 20.6% (95% CI 18.1–23.2) of those 953 cars that failed were not tested again. Did this failure stay fixed?
Follow-up uses the DVSA vehicle_id, which is stable across annual releases, so the same physical car is compared from its 2024 test to its 2025 test. Browse the MOT prognosis registry. Source: DVSA Anonymised MOT tests and results, 2024 and 2025 extracts (Class 4). Contains public sector information licensed under the Open Government Licence v3.0.
Related noise, emissions and leaks advisories
Before you agree to the work
A fault or an advisory is a quote waiting to happen. These pages set out what a garage has to tell you, what a comparable written quote should include, and what you can do if the bill is not what you agreed.
- Estimates, quotes and extra work — what a price has to cover, and when a garage may charge more than it first said.
- What a diagnostic test costs — what the fee should include, and when it should come off the repair.
- Tools — when to buy and when to skip — how to choose a diagnostic tool, and when a garage visit is cheaper than owning one.
- Choosing a garage you can check — what to verify before you hand over the keys.
- Your rights after a car repair — what to do when the work is not right, and how to put it in writing.
Frequency: DVSA Anonymised MOT tests and results, 2025 extract (Class 4). Wording follows the DVSA inspection manual. Contains public sector information licensed under the Open Government Licence v3.0.