MOT advisory explained
“Brake hose has slight corrosion to ferrule”
A spot of rust on a metal collar the size of a thimble. It is one of the least urgent brake advisories, and one of the most persistent: a third of cars that get it get it again. Here is what a ferrule is and when rust on one starts to matter.
A ferrule is the crimped steel sleeve that clamps the end of a rubber brake hose onto its metal connector. The tester saw surface rust on one. The crimp is tight, the hose is sound and nothing is leaking.
3.4% fail on a brake hose at the next test and 32.0% are advised again with no change. The ferrule is plated steel in a wet place, so it rusts on most cars eventually. Light rust on it does nothing.
The part to worry about on a rusty underside is not this one. Corroded metal brake pipes fail three times as often, and a pipe can rust through and leak. A ferrule is a thick collar around a hose that is doing the sealing by itself.
A “brake hose has slight corrosion to ferrule” advisory means there is surface rust on the crimped metal collar at the end of a flexible brake hose, while the hose is secure and not leaking, so the car passes. No repair is needed at this stage. According to DVSA MOT data analysed by PriceMyRepair, 3.4% of 1.3 million such advisories followed to the next test failed on a brake hose, and 32.0% were given the same advisory again.
What a ferrule does, and how it fails
A crimp, not a seal. The hose is pushed over a ribbed metal insert and the ferrule is squeezed down around it at the factory. The grip comes from the rubber being compressed between insert and ferrule. The ferrule only has to stay the shape it was crimped to.
When rust matters. Surface rust on the outside changes nothing. The problem comes years later if rust builds up under the plating and the steel swells and flakes. A ferrule that has lost thickness can relax its grip, and rust scale at the open end can cut into the rubber where the hose flexes. That is the point at which testers fail it.
What testers write. The notes are about how many, not how bad: “both”, “both sides”, “all”, “all four”. When one ferrule has rusted, the rest have had the same weather, and testers tend to record the set.
Will it fail next year?
This advisory has been written 4,340,439 times. 1,265,734 of those can be traced to the same car’s following MOT.
| What happened at the next test | Share |
|---|---|
| Failed on the same component | 3.4% |
| Same advisory recorded again | 32.0% |
According to DVSA MOT data analysed by PriceMyRepair: 1,265,734 advisories followed to the same vehicle’s next test. Rows can overlap.
For a brake component this is a low figure. It is below the rubber part of the same hose, which fails 5.1% of the time after a “slightly deteriorated” advisory, and a long way below corroded brake pipes at 10.1%.
The repeat rate is what stands out. About a third come back the following year in the same words. Nobody replaces a working brake hose for a rusty collar, and they are usually right not to.
| Advisory wording | Fails on same part | Advised again | Followed |
|---|---|---|---|
| Brake pipe corroded, covered in grease or other material | 10.1% | 44.4% | 7,889,073 |
| Service brake binding | 9.3% | 14.4% | 2,418,487 |
| Brake pad(s) wearing thin | 7.2% | 16.9% | 13,888,197 |
| Brake hose slightly deteriorated | 5.1% | 33.8% | 735,057 |
| Brake disc worn, pitted or scored, | 3.7% | 31.2% | 15,014,091 |
| Brake hose has slight corrosion to ferrule | 3.4% | 32.0% | 1,265,734 |
| Brake disc worn, | 2.6% | 12.9% | 3,690,262 |
It starts early and never stops climbing. There are a few cases even at 3–4 years. By 20 years and over it is on 23.5 of every 1,000 tests. The share that fail next time rises with it, from 0.9% on young cars to 4.4% on the oldest, as light rust has had time to become heavy rust.
| Age of car | Per 1,000 tests | Fails on same part | Followed |
|---|---|---|---|
| 3–4 years | 0.3 | 0.9% | 8,255 |
| 5–6 years | 1.0 | 1.0% | 30,585 |
| 7–9 years | 3.2 | 1.5% | 131,225 |
| 10–12 years | 8.5 | 2.6% | 281,525 |
| 13–15 years | 16.1 | 3.7% | 372,238 |
| 16–19 years | 22.7 | 4.4% | 310,363 |
| 20 years and over | 23.5 | 4.4% | 119,344 |
The list of models below has nothing in common with the list for perished hose rubber, which is led by BMWs. Rubber and plated steel age in different ways, and the data splits them cleanly.
The positions differ as well. Perished rubber is mainly a front hose problem, where the hose flexes with the steering. Rusty ferrules are mainly at the rear, in the spray thrown up by the front wheels.
If you have both advisories on the same hose, replace it. The hose is old at both ends and in the middle.
Exact wording on your certificate
Singular and plural are recorded as separate wordings with the same code. The failure version says how much corrosion is too much.
| Line on the certificate | Result | Code |
|---|---|---|
| Brake hose has slight corrosion to ferrule | Advisory — pass | 1.1.12 (f) (i) |
| Brake hose has slight corrosion to ferrules | Advisory — pass | 1.1.12 (f) (i) |
| Brake hose ferrules excessively corroded | Major — fail | 1.1.12 (f) (i) |
More than half of all instances are at the rear once the entries marked just “rear” are included. About one in eleven has no position at all, which usually means the tester was describing every hose on the car.
| Position written by the tester | Share of all instances |
|---|---|
| Offside rear | 21% |
| Nearside rear | 20% |
| Offside front | 16% |
| Nearside front | 13% |
| Rear | 13% |
| No position recorded | 9% |
From 4,340,439 recorded instances. Testers can add their own note after the standard wording. The most common on this advisory: “both” (172,217), “both sides” (123,319), “all” (114,917), “both rear” (39,331), “both front” (22,713), “nearside and offside” (21,953), “x2” (18,546), “n/s and o/s” (13,877).
Is there anything to pay for?
Not at this stage. A ferrule cannot be replaced separately, so the eventual repair is a new hose, and that is only needed when the rust is heavy. We do not publish a range for brake hoses because corroded unions make the labour unpredictable. If you are having other brake work done, it is a sensible time to ask for a price. Related brake prices are on the brake caliper replacement cost page.
Can I still drive with this advisory?
There is nothing to feel through the pedal and nothing to check between tests. The one sign worth acting on is dampness or fluid at the end of a hose, which means the joint is leaking and needs attention at once.
Enter your reg to see every brake advisory your car has collected. If this one has appeared for several years with the same wording, it is behaving exactly as the data predicts.
Which cars get this advisory most?
It appears on 7.8 of every 1,000 tests across all vehicles, and between two and a half and four times as often on the models below.
| Model | Per 1,000 tests | Vs all cars | Tests |
|---|---|---|---|
| Land Rover Discovery | 32 | 4.1× | 1,610,504 |
| Saab 9-3 | 32 | 4.1× | 589,429 |
| Vauxhall Agila | 31 | 4.0× | 435,853 |
| Peugeot 206 | 26 | 3.4× | 1,061,894 |
| Suzuki SX4 | 26 | 3.3× | 418,443 |
| Suzuki Swift | 22 | 2.8× | 1,305,473 |
| Fiat Punto | 22 | 2.8× | 1,031,944 |
| Jaguar XF | 21 | 2.7× | 969,012 |
| Honda Jazz | 21 | 2.6× | 3,292,357 |
| Vauxhall Meriva | 19 | 2.4× | 1,207,698 |
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.
It is a mixed list with no single maker in charge: the Land Rover Discovery, Saab 9-3 and Vauxhall Agila lead, and Suzuki appears twice, with the Suzuki SX4 and Suzuki Swift. The Vauxhall Agila is a Suzuki design as well.
Most are cars that last well into their teens and are still being tested when the underside has had fifteen winters. The plating on a small steel collar was never meant to look new at that age.
What to do next
- Nothing, if it is surface rust. This is one of the few advisories where doing nothing is the correct response.
- Look at the hose next to the ferrule. Cracked rubber right at the collar matters more than the rust on it. That is where a hose flexes most.
- Deal with brake pipes first. If the same certificate mentions corroded pipes, that is where the money should go.
- Replace the hose when other brake work is due. With the brakes already apart and being bled, a new hose adds little. It is the cheap moment to clear the advisory.
Brake hose ferrule corrosion FAQ
What is a brake hose ferrule?
It is the crimped steel collar at each end of a flexible brake hose that clamps the rubber onto its metal connector. It is part of the hose and cannot be replaced separately.
What does brake hose has slight corrosion to ferrule mean?
There is surface rust on that collar. The hose is secure and not leaking, so it is an advisory and the car passes. No repair is needed.
Will a corroded ferrule fail the next MOT?
Rarely. According to DVSA MOT data analysed by PriceMyRepair, 3.4% of 1.3 million such advisories failed on a brake hose at the next test, and 32.0% were simply advised again.
Is it dangerous?
Not at the advisory stage. It becomes a problem only when rust has swollen or flaked the collar enough to loosen its grip or cut into the hose. Fluid at the end of a hose is the sign to act on immediately.
Do I need to replace the brake hose?
Not for slight corrosion alone. Replace it when the rust is heavy, when the rubber beside the ferrule is cracked, or conveniently when other brake work is being done. Any prices we publish are estimates and final quotes come from garages.
Which cars get this advisory most?
The Land Rover Discovery, Saab 9-3 and Vauxhall Agila, at around four times the average rate. It is mostly seen on cars over ten years old.
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 4,340,439 times; 1,265,734 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.