Honda Cb400-4 common MOT failures and failure rate
What a Honda Cb400-4 fails its MOT on, from real DVSA test data, and the part that resolves each item.
Based on 180 MOT tests in DVSA data.
About 13.3% of MOT tests recorded on the Honda Cb400-4 in DVSA data end in a failure. The same handful of items account for most of them.
Its most common failure is other, which makes up 33.3% of the Honda Cb400-4's failures, followed by other, lamps & electrical, steering, tyres. 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
This covers a range of smaller items, from a non-working horn to a warning light left on.
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.
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.
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.
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.
Structural failures are corrosion in load-bearing areas, sharp edges, or insecure panels. These are inspection-and-welding jobs rather than a simple bolt-on part, so weigh them against the value of the car.
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