Every MOTis an Odyssey.

There's no way to know for certain until the test itself. Around a third of MOTs result in a fail, and it's often for reasons drivers didn't spot beforehand, from worn tyres to a fault in the braking or suspension system. Age and mileage make a difference too, so an older or higher-mileage car carries more risk of turning up an issue.

Checking the basics helps: tyre tread and condition, all your lights, washer fluid, and any cracks in the windscreen within the driver's sightline. But these checks only catch what's visible. Plenty of fails come down to wear you can't see or assess without testing equipment, such as brake performance or emissions.

Want a clearer answer before you book? Try our MOT predictor. Just enter a few details about your car and it will tell you how likely you are to pass, plus what it's most likely to fail on, so you know exactly what to check first.

No, a service light on its own will not fail your MOT. The MOT test checks whether your car is safe and roadworthy, not whether it's been serviced on schedule. Servicing and MOT testing are two separate things.

That said, don't ignore the light. A service warning can point to an underlying issue, such as worn brakes or low oil, that could show up as a genuine MOT fault. If you're due a service, it's worth booking one alongside your MOT so any real problems get caught early rather than causing a fail.

It depends on the size and location of the crack. Any damage within the driver's direct line of sight (roughly a 290mm band in front of the driver, in line with the steering wheel) must be no bigger than 10mm across. Outside that zone but still within the area the wipers clean, damage must be no bigger than 40mm. Anything larger, or a crack that spreads dangerously, will fail.

A small chip well outside the swept area is unlikely to cause a fail on its own, but it's worth getting it looked at before it spreads.

Not necessarily, and this is one to take seriously. Since 2018, an illuminated engine management light has been a standalone reason for failure if it's showing a fault once the engine is running. Testers check that the light comes on with the ignition and goes off once the engine starts. If it stays on, or flickers, that's treated as a genuine fault and results in a fail.

Don't assume it's minor. Get the fault code read before your test so you know what you're dealing with.

Usually, but check your tyres properly rather than assuming it's fine. The tyre pressure warning light isn't an MOT test item on its own, so a light triggered by slight under-inflation won't fail you by itself. Testers will still check your actual tyre pressure, tread depth, and condition regardless of what the dashboard says, and if the light is flagging a genuine problem, such as a slow puncture or significant wear, that underlying issue can fail your car.

Top up your tyres to the correct pressure before your test and check the light clears.

It depends on which mirror and how broken it is. Every car needs at least two exterior mirrors, or one exterior mirror plus an interior mirror, and they must give the driver a clear view behind and to the side. Your car will fail if a required mirror is missing, so badly cracked or clouded that visibility is impaired, or not securely fixed in place.

A small chip or scratch that doesn't affect the view is unlikely to be a problem. A shattered, missing, or loose mirror will be marked as a fault.

This one comes down to security, not appearance. Tape itself isn't automatically a fail. What matters is whether the mirror is held firmly in position and won't move or fall off while driving. If a taped mirror passes that test and gives a clear rear view, it can pass. If it's loose, wobbly, or likely to detach, it will fail.

For peace of mind, it's worth getting a taped mirror properly refitted or replaced before your test rather than leaving it to chance.

The MOT covers a wide range of checks, and most failures come down to a handful of common areas:

• Lights – blown bulbs, misaligned headlights, or faulty indicators
• Tyres – low tread depth, damage, or incorrect pressure
• Brakes – worn pads, discs, or an imbalanced braking system
• Windscreen – cracks or chips within the driver's line of sight
• Wipers and washers – not clearing the windscreen properly or an empty washer bottle
• Suspension – worn components or leaks
• Exhaust and emissions – excessive smoke or emissions above the legal limit
• Number plates – illegible, damaged, or incorrectly displayed

Many of these are quick, low-cost fixes if you catch them before your test. A pre-MOT check can flag issues early and save you a second trip to the test centre.