Brake pipes corroding
Last reviewed 22 October 2026. General information, not advice about a particular car.
Fix soon Will get worse and may fail the next MOT. Budget for it in the next few months.
Metal brake lines rust from the outside in. "Slightly corroded" is common on older cars and is an advisory; "excessively corroded" is a fail because the pipe can split and you lose braking. Get it looked at.
What the wording on the certificate means
You’ll usually see something like “Brake pipe slightly corroded”, often with a position such as “nearside front” (the passenger side) and a reference to the MOT inspection manual in brackets.
The metal pipes that carry brake fluid along the underside of the car are starting to rust. “Slightly corroded” means the surface is affected but the pipe isn’t weakened yet.
Why it matters
If a brake pipe rusts through, it can leak fluid suddenly and the brakes can lose pressure. That’s why badly corroded pipes are a fail, and why this advisory tends to get worse year by year on cars used on salted winter roads.
What to do
- Ask the garage to check it again at the next service rather than waiting for the MOT.
- When pipes are replaced, copper-nickel pipe (often called Kunifer) resists corrosion much better than plain steel.
- If the brake pedal ever feels soft or sinks, stop driving and get it checked.
Will it fail the next MOT?
An advisory isn’t a fail, and the car can be driven, as long as it stays roadworthy. A brake pipe that is excessively corroded, damaged or leaking is a major or dangerous defect and a fail.
If you’re buying a car with this advisory
If this advisory has appeared at several MOTs in a row, expect to replace the pipes soon. If the same advisory shows up at test after test, it has probably been left unrepaired.
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