The MOT Files

Known faults, from the test record

MG 3 common problems

What fails on the MG 3 at MOT, which parts are behind it, and how each model year compares. From 24,958 DVSA test records.

Data updated

Quick answer

The MG 3's most common MOT problems are tyres, wiper blades and washers, bulbs and lamps, recorded in 38.0%, 18.9% and 18.6% of failed tests respectively. By model year, 2022 cars pass most often (85.1%) and 2015 cars least (65.7%), 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 MG 3 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 24,958 cars.

By component

What wears out on a 3

Failure items grouped by the part behind them, with the share of failed MG 3 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

    38.0% 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.

    • “Tyre tread depth not in accordance with the requirements” — explained11.8%
    • “A tyre cords visible or damaged” — explained10.9%
    • “A tyre seriously damaged” — explained9.1%
    • “A tyre seriously damaged” — explained2.6%

    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

    18.9% 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” — explained11.8%
    • “Windscreen washers not working or not providing sufficient fluid to clear the windscreen” — explained4.5%
    • “Windscreen washers not working or not providing sufficient fluid to clear the windscreen” — explained2.6%

    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.Bulbs and lamps

    18.6% of failed tests

    Filament bulbs simply expire; the cheapest and most avoidable failure on the test, and one of the most recorded.

    • “A headlamp or light source missing, inoperative or more than ½ not functioning in the case of LED” — explained7.0%
    • “Stop lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning” — explained4.4%
    • “A lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning” — explained3.6%
    • “A headlamp or light source missing, inoperative or more than ½ not functioning in the case of LED” — explained2.2%

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

  4. 4.Parking brake

    13.3% of failed tests

    Cables stretch and seize, rear shoes and adjusters wear; efficiency is measured on the roller tester against the vehicle's weight.

    • “Parking brake efficiency below minimum requirement” — explained8.4%
    • “Parking brake inoperative on one side” — explained2.3%
    • “Parking brake efficiency less than 50% of the required value” — explained1.5%
    • “Parking brake lever has excessive movement indicating incorrect adjustment” — explained1.0%

  5. 5.Suspension bushes

    13.0% of failed tests

    Rubber bushes in arms and links perish and split with age and load; the most recorded suspension item on the test.

    • “A suspension pin, bush or joint excessively worn” — explained10.6%
    • “A suspension pin, bush or joint excessively worn” — explained1.6%
    • “A suspension joint dust cover missing or no longer prevents the ingress of dirt etc” — explained0.8%

    Across all cars, suspension bushes failures climb 20-fold between three and fifteen years, peaking at 15+ years. How long suspension bushes last

  6. 6.Coil springs

    8.9% of failed tests

    Springs fatigue and corrode where the coating chips, then snap, often at the bottom coil; potholes and salt accelerate it.

    • “A spring or spring component fractured or seriously weakened” — explained8.9%

    Across all cars, coil springs failures climb 20-fold between three and fifteen years, peaking at 12–14 years. How long coil springs last

  7. 7.Brake pads and shoes

    8.6% 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” — explained7.7%
    • “Brake lining or pad worn down to wear indicator” — explained0.9%

    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

  8. 8.Headlamp aim

    7.8% 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” — explained3.7%
    • “Headlamp aim unable to be tested” — explained2.2%
    • “The aim of a headlamp is not within limits laid down in the requirements” — explained1.8%

By registration year

3 problems by year

MOT pass rate for MG 3 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. The step at 2016, up 5.5 points, is larger than wear explains and most likely marks a change in the cars themselves.

201467%
201566%−1.7
201671%+5.5
201770%−1.6
201872%+2.5
201975%+3.2
202079%+4.0
202182%+2.7
202285%+3.2

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 3 owners about

Advisories are the same parts a year or two earlier. Share of all MG 3 tests carrying an advisory for each.

Go deeper

The rest of the 3 file

Common questions

What are the most common problems with a MG 3?
Going by what fails the MOT, tyres (recorded in 38.0% of failed tests), wiper blades and washers (recorded in 18.9% of failed tests), and bulbs and lamps (recorded in 18.6% of failed tests). These are the items testers actually record across 24,958 tests, not reports from owners, so they describe what goes wrong at the point where it has to be fixed.
Which MG 3 year is the most reliable?
By MOT pass rate, MG 3 cars registered in 2022 do best at 85.1% and 2015 cars do worst at 65.7%. 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. The largest such step is at 2016, up 5.5 points on 2015.
Is the MG 3 reliable?
The MG 3 passes 75.1% 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 MG 3?
Start with what fails most: tyres, wiper blades and washers, bulbs and lamps. 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