Why does my exhaust rattle?

Either a loose heat shield, a corroded exhaust mount, or a broken catalytic converter / centre box internal baffle.

Here's a quick, honest answer from a working UK mechanic — what causes it, what it costs to fix, and what to do next.

Is it dangerous? — Loose heat shields can drop into the road — fix promptly. A failed cat will eventually fail emissions at MOT.

Will it fail the MOT? — Excessive noise, loose components, and emission failures are all MOT fails.

Bob's Mechanical Repairs — independent family-run garage in Birnam, Dunkeld, Perthshire. Call 01350 727 276 or email bob@bobsmechanicalrepairs.co.uk.