Riley 12/4 common MOT failures and failure rate
What a Riley 12/4 fails its MOT on, from real DVSA test data, and the part that resolves each item.
Based on 81 MOT tests in DVSA data.
About 7.4% of MOT tests recorded on the Riley 12/4 in DVSA data end in a failure. The same handful of items account for most of them.
Its most common failure is brakes, which makes up 66.7% of the Riley 12/4's failures, followed by brakes, fuel system, lamps & electrical. 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
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.
Fuel-system failures are leaks or an insecure filler cap.
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.
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