MOT failure rate and common problems for the Mercedes 209, and how to check your own car by registration.
Updated 05 September 2026.
Mercedes 209 MOT failure rate
What a Mercedes 209 fails its MOT on, and the part that fixes each.
What it fails on, and why
Brake failures cover worn pads and discs, an imbalance between wheels, corroded or scored discs, or a binding caliper. Braking efficiency is measured on a rolling road, so a spongy or pulling brake shows up as a low reading.
Tyres fail for tread below the 1.6mm legal limit across the central three-quarters, uneven or exposed-cord wear, or sidewall damage. The tester inspects all four; a single illegal tyre is a fail.
Lighting is the single most common MOT failure and the cheapest to put right. A blown headlight, brake-light or number-plate bulb, a cracked lens, or a headlamp beam that points too high or low will all fail. Most are a two-minute bulb swap.
Suspension failures usually mean a worn or snapped coil spring, a leaking shock absorber, or play in a lower arm ball joint or bush. The tester checks for corrosion, fractures and excessive movement. A broken front spring is one of the most common failures on higher-mileage cars and is a straightforward replacement.
A missing, damaged, dirty or incorrectly-spaced number plate, or one using the wrong font, will fail. A replacement plate is inexpensive.
Seat-belt failures are frays, cuts, corroded anchorages, or a belt that will not lock under a sharp pull or retract properly.
The parts that fix each
If your car has just failed, you have 10 working days to fix the items and get a free partial retest. Confirm the exact fitment against your registration or VIN before buying.
Other models
Questions and answers
What is the MOT failure rate of the Mercedes 209?
It fails 16.0% of its MOT tests across the DVSA record, from 75 tests.
What do these cars fail their MOT on most?
The most common failure area is brakes, at 33.3% of this model's failures.