Common MOT failures and how to avoid them

More than a quarter of cars are cited as failing their MOT the first time they're tested, and DVSA data consistently points to the same handful of categories being responsible for the bulk of those failures. Knowing what they are makes it genuinely possible to catch and fix the most likely problems before you book your test.

Lighting and electrical equipment is consistently the single most common cause of MOT failure, cited as responsible for around one in five failed tests. This covers a range of faults that are often simple and cheap to fix once spotted — a blown headlight, brake light or indicator bulb, a cracked lens, or a faulty number plate light. It's also one of the easiest categories to check yourself before your test: walk around the car with the engine running and headlights, indicators, brake lights, fog lights, hazards and the number plate light all switched on, ideally with a second person checking from outside while you operate the switches, or by reversing up to a reflective surface like a shop window or garage door.

Suspension issues cause more than one in ten MOT failures, typically things like worn shock absorbers, damaged springs, or perished suspension bushes. These are harder for most owners to check reliably without getting the car up on a ramp, but a rough sign worth paying attention to is excessive bouncing after going over a bump, or a knocking noise from a corner of the car when driving over uneven surfaces — either is worth mentioning to a garage for a proper check before your MOT is due.

Tyres are another major category, most commonly failing on tread depth below the legal minimum of 1.6mm, measured across the central three-quarters of the tyre's width and around its full circumference. This one is genuinely easy to check yourself — a 20p coin pushed into the tread groove should have the outer rim of the coin fully covered by tread if you're comfortably above the legal minimum; if the rim is visible, it's worth having the tyre properly measured and likely replaced before your test. Worth checking tyre condition more broadly too — bulges, cuts and uneven wear can all cause a failure independent of tread depth.

Brakes cause roughly one in ten MOT failures, covering issues like worn brake pads or discs, a handbrake that doesn't hold effectively, or an imbalance between the two sides of the car when braking. This is harder to self-check with much confidence, but noticeable symptoms worth acting on before your MOT include a spongy or long-travel brake pedal, grinding or squealing noises when braking, or the car pulling to one side under braking.

Visibility-related failures — largely windscreen damage and issues with wipers or washers — are also regularly cited among the leading categories. A chip or crack in the driver's direct line of sight is treated more strictly than damage elsewhere on the glass, since it obstructs the driver's view in the area that matters most; even a fairly small chip in that zone can be enough to fail. Checking your windscreen for chips, making sure both wipers clear the glass properly without smearing or judder, and topping up washer fluid so it actually sprays when tested are all quick, free checks worth doing before your test date.

Beyond these top categories, a broader pre-MOT walk-around is worth doing a week or so before your booked test, giving you time to sort anything you find rather than discovering it on the day. Check all the lights, tyre tread and condition, that the horn works, that seatbelts extend and retract smoothly with no fraying, and that there's no visible fluid leaking underneath the car. None of this replaces a proper inspection by a garage, but catching the obvious, common failure points yourself — particularly lighting and tyres, which together account for a large share of failures and are genuinely simple to check — meaningfully improves your odds of a first-time pass and avoids paying for a failed test and a second visit.

Timing your check matters too. A week or so before the test gives enough time to order a bulb, book a tyre fitting, or get a wiper blade replaced without any last-minute panic, whereas checking the morning of your MOT leaves no room to actually fix anything you find. Some garages also offer a paid pre-MOT check specifically aimed at catching likely failure points before the official test — worth considering if your car is older, has a history of advisories on previous tests, or simply hasn't had much attention recently, since the cost of a pre-check is usually a fraction of what a failed test plus a second visit ends up costing once you add the retest fee and any last-minute repair carried out under time pressure.

Frequently asked questions