The MOT Files

Known faults, from the test record

Mazda CX-30 common problems

What fails on the Mazda CX-30 at MOT, which parts are behind it, and how each model year compares. From 20,888 DVSA test records.

Data updated

Quick answer

The Mazda CX-30's most common MOT problems are tyres, wiper blades and washers, brake pads and shoes, recorded in 52.0%, 22.9% and 21.7% of failed tests respectively. By model year, 2022 cars pass most often (92.7%) and 2020 cars least (89.5%), though most of that gap is age. Every figure here is what testers recorded, not what owners reported.

A “common problems” list is usually a forum thread: whoever had the worst day writes the longest post. This one is built the other way, from every Mazda CX-30 that took an MOT last year and what the tester wrote down. It cannot see breakdowns, electrical gremlins or a gearbox that hunts, because the test does not check those. What it can see, it sees across 20,888 cars.

By component

What wears out on a CX-30

Failure items grouped by the part behind them, with the share of failed Mazda CX-30 tests recording each. A part can carry several DVSA wordings; they are listed beneath. One failed test often lists several items, so shares do not sum to 100%.

  1. 1.Tyres

    52.0% of failed tests

    Tread wears with every mile and sidewalls age and take kerb damage; the legal minimum is 1.6 mm across the central three-quarters.

    • “A tyre seriously damaged” — explained22.2%
    • “Tyre tread depth not in accordance with the requirements” — explained21.5%
    • “A tyre cords visible or damaged” — explained3.9%
    • “A tyre seriously damaged” — explained2.9%

    Across all cars, tyres failures run at a similar rate at every age, because they are replaced on a cycle rather than wearing out with the car. How long tyres last

  2. 2.Wiper blades and washers

    22.9% of failed tests

    Rubber blades harden and split within a year or two; washer jets block and pumps fail.

    • “Wiper blade missing or obviously not clearing the windscreen” — explained20.2%
    • “Windscreen washers not working or not providing sufficient fluid to clear the windscreen” — explained2.0%
    • “Windscreen washers not working or not providing sufficient fluid to clear the windscreen” — explained0.7%

    Across all cars, wiper blades and washers failures run at a similar rate at every age, because they are replaced on a cycle rather than wearing out with the car. How long wiper blades and washers last

  3. 3.Brake pads and shoes

    21.7% of failed tests

    Friction material wears with use; the MOT limit is 1.5 mm and a pad that thin is close to metal on metal.

    • “a brake lining or pad worn below 1.5mm” — explained20.2%
    • “Brake lining or pad worn down to wear indicator” — explained1.0%
    • “Brake lining or pad missing or incorrectly mounted” — explained0.5%

    Across all cars, brake pads and shoes failures run at a similar rate at every age, because they are replaced on a cycle rather than wearing out with the car. How long brake pads and shoes last

  4. 4.Shock absorbers

    10.0% of failed tests

    Seals wear and the damper leaks fluid or loses its action; failure is for a leak or no damping, not for being tired.

    • “A shock absorber damaged to the extent that it does not function or showing signs of severe leakage” — explained9.6%
    • “A shock absorber which has negligible damping effect” — explained0.4%

    Across all cars, shock absorbers failures climb 7-fold between three and fifteen years, peaking at 15+ years. How long shock absorbers last

  5. 5.Brake discs

    9.5% of failed tests

    Discs thin with each pad set and pit or corrode when lightly used; failure is for significant wear, fracture or insecurity, advisory for surface condition.

    • “Brake disc or drum significantly and obviously worn” — explained6.1%
    • “Brake disc or drum excessively weakened, insecure or fractured” — explained1.7%
    • “Excessive fluctuation in brake effort through each wheel revolution.” — explained1.7%

    Across all cars, brake discs failures climb 3-fold between three and fifteen years, peaking at 12–14 years. How long brake discs last

  6. 6.Engine management

    6.5% of failed tests

    The MIL lamp lit is a failure in itself, whatever the stored code; the fault codes section explains what lies behind it.

    • “Engine MIL illuminated indicating a malfunction” — explained6.5%

  7. 7.Tyre pressure sensors

    2.1% of failed tests

    Valve-mounted sensors have sealed batteries that expire after roughly seven to ten years; a system fault lamp is a failure on cars first used from 2012.

    • “A tyre pressure monitoring system malfunctioning or obviously inoperative” — explained2.1%

  8. 8.Headlamp aim

    1.9% of failed tests

    Aim drifts with sagging suspension, a knocked lamp or a botched bulb change; adjustment, not a part.

    • “The aim of a headlamp is not within limits laid down in the requirements” — explained1.0%
    • “The aim of a headlamp is not within limits laid down in the requirements” — explained0.9%

By registration year

CX-30 problems by year

MOT pass rate for Mazda CX-30 cars by the year they were first registered, from years with at least 1,000 tests. Every car in a row is the same age, so the rate is raw. Neighbouring years differ by a year of wear — a step of a point or two is age. No single step here is large enough to point at a generation change.

202090%
202192%+2.3
202293%+1.0

Last column: change on the previous year, in points. Years registered within the last three years have not yet been tested and are not shown.

Before it fails

What testers warn CX-30 owners about

Advisories are the same parts a year or two earlier. Share of all Mazda CX-30 tests carrying an advisory for each.

Go deeper

The rest of the CX-30 file

Common questions

What are the most common problems with a Mazda CX-30?
Going by what fails the MOT, tyres (recorded in 52.0% of failed tests), wiper blades and washers (recorded in 22.9% of failed tests), and brake pads and shoes (recorded in 21.7% of failed tests). These are the items testers actually record across 20,888 tests, not reports from owners, so they describe what goes wrong at the point where it has to be fixed.
Which Mazda CX-30 year is the most reliable?
By MOT pass rate, Mazda CX-30 cars registered in 2022 do best at 92.7% and 2020 cars do worst at 89.5%. Most of that ordering is simply age — newer cars pass more — so read the year table for steps larger than a couple of points between neighbouring years; those mark a change in the cars rather than the calendar.
Is the Mazda CX-30 reliable?
The Mazda CX-30 passes 91.3% of MOTs unadjusted; its fleet is too narrow in age or mileage for a fair national comparison. An MOT measures roadworthiness on the day rather than breakdowns or running costs, so this is a reliability measure in the narrow sense: how often the car meets the legal standard, and what stops it.
What should I check when buying a used Mazda CX-30?
Start with what fails most: tyres, wiper blades and washers, brake pads and shoes. Then read the car's own MOT history for advisories carried year to year without repair — the model tells you what to expect, the history tells you whether this owner dealt with it.

Analysis built from DVSA data of