Smc Unknown common MOT failures and failure rate
What a Smc Unknown fails its MOT on, from real DVSA test data, and the part that resolves each item.
Based on 171 MOT tests in DVSA data.
About 21.1% of MOT tests recorded on the Smc Unknown in DVSA data end in a failure. The same handful of items account for most of them.
Its most common failure is suspension, which makes up 38.9% of the Smc Unknown's failures, followed by suspension, lamps & electrical, other, brakes. Each item below links to the part that resolves it. Confirm the exact fitment against your registration or VIN before buying, and have safety-critical work done by a competent mechanic.
What it fails on, and why
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.
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.
This covers a range of smaller items, from a non-working horn to a warning light left on.
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.
A missing, damaged, dirty or incorrectly-spaced number plate, or one using the wrong font, will fail. A replacement plate is inexpensive.
Steering faults are typically worn track-rod ends or ball joints, play in the rack, or a split gaiter letting grease out and dirt in. Excessive free play at the wheel fails.
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. These are the usual parts; confirm the exact fitment against your registration or VIN before buying.
Other models
Sources: DVSA MOT History API: MOT test results and defect data ยท DVSA MOT testing data for Great Britain