There's serious corrosion in the structure close to where a suspension component bolts to the car. The MOT treats the area around load-bearing mountings differently from the rest of the bodywork, because rust there affects whether the suspension stays attached.
Wording as it commonly appears on an MOT certificate: “Suspension component mounting prescribed area excessively corroded”.
What does it mean?
There's serious corrosion in the structure close to where a suspension component bolts to the car. The MOT treats the area around load-bearing mountings differently from the rest of the bodywork, because rust there affects whether the suspension stays attached.
How serious is it?
Usually recorded as: Major, Dangerous. The tester assesses the actual vehicle on the day, so your certificate is what counts.
What normally causes it?
- Age and road salt, particularly on cars that have spent winters on gritted roads
- Mud packing into a chassis leg or subframe mount and holding moisture year-round
- Earlier repairs where a panel was covered up rather than cut out
What a mechanic would check
Get it on the ramp, clean the area back and tap it with a light hammer — sound metal rings, rotten metal doesn't. That tells you whether it's surface scale or whether the section is actually holed. I'd photograph it so you can see exactly what we're dealing with before you decide anything.
What might need replacing
- Cutting out and welding in new metal, then sealing and underbody protection
- In severe cases, an honest conversation about whether the car is economical to repair
Can you still drive it?
This can be recorded as Dangerous depending on severity. Corrosion around a suspension mount is not something to run on — get it assessed properly and don't take a guess from photographs alone.
Repair cost
Welding is priced by time and access, so it can range from a modest repair to more than an older car is worth. Get it looked at and get an honest opinion on whether it's worth doing before you commit.
Before the retest
Suspension parts such as springs, shock absorbers and drop links are normally replaced in pairs across an axle so the car sits level and handles evenly. Any work that disturbs the steering or suspension geometry is worth following with a wheel alignment check, otherwise you can pass the retest and still wear out a new pair of tyres within months. Listen for the original knock again on a bumpy road before the retest — if it is still there, something was missed.
Retest rules
If the vehicle stays at the test centre for repair and is retested within 10 working days, a partial retest is often free; some items qualify for a free retest if you bring the car back by the end of the next working day. The exact conditions are set out on GOV.UK, so confirm with the test centre before you leave. A major or dangerous failure means the car cannot legally be driven away unless the previous MOT is still valid and nothing dangerous was recorded — check your certificate first.
Related help
More suspension failures · MOT failure decoder · Ask a mechanic about your certificate
This is general guidance from a UK mechanic, not a substitute for a physical inspection. Only the tester who inspected your vehicle can confirm what was recorded and why.