The MOT Files

Known faults, from the test record

MG TF common problems

What fails on the MG TF at MOT, which parts are behind it, and how each model year compares. From 8,683 DVSA test records.

Data updated

Quick answer

The MG TF's most common MOT problems are parking brake, suspension arms and mountings, catalytic converter and emissions, recorded in 25.7%, 25.3% and 22.4% of failed tests respectively. By model year, 2005 cars pass most often (72.2%) and 2003 cars least (66.4%), 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 TF 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 8,683 cars.

By component

What wears out on a TF

Failure items grouped by the part behind them, with the share of failed MG TF 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.Parking brake

    25.7% 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” — explained18.6%
    • “Parking brake inoperative on one side” — explained4.6%
    • “Parking brake efficiency less than 50% of the required value” — explained2.5%

  2. 2.Suspension arms and mountings

    25.3% of failed tests

    Arms bend on impact and mountings corrode into the body; a corroded mounting is a structural item and fails as one.

    • “The strength or continuity of the load bearing structure within 30cm of any sub-frame, spring or suspension component mounting (a 'prescribed area') is significantly reduced or inadequately repaired” — explained9.8%
    • “A suspension component excessively damaged or corroded” — explained8.4%
    • “The strength or continuity of the load bearing structure within 30cm of any sub-frame, spring or suspension component mounting (a 'prescribed area') is significantly reduced or inadequately repaired” — explained4.1%
    • “A suspension component excessively damaged or corroded” — explained3.0%

  3. 3.Catalytic converter and emissions

    22.4% of failed tests

    Catalysts degrade with age and misfires; a failed emissions reading is usually the catalyst, a lambda sensor or a tired engine.

    • “Lambda coefficient outside the default limits or the range specified by the manufacturer” — explained8.2%
    • “Emissions levels exceed the manufacturer's specified limits” — explained6.5%
    • “Emissions levels exceed default limits” — explained3.9%
    • “Emissions levels exceed default limits” — explained3.8%

  4. 4.Wiper blades and washers

    17.8% 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” — explained8.4%
    • “Windscreen washers not working or not providing sufficient fluid to clear the windscreen” — explained5.7%
    • “Windscreen washers not working or not providing sufficient fluid to clear the windscreen” — explained3.7%

    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

  5. 5.Tyres

    14.1% 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” — explained5.7%
    • “Tyre tread depth not in accordance with the requirements” — explained3.0%
    • “A tyre cords visible or damaged” — explained2.9%
    • “A tyre seriously damaged” — explained2.5%

    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

  6. 6.Ball joints

    10.8% of failed tests

    Steering and suspension ball joints wear internally and their dust covers split; excessive play fails.

    • “A steering ball joint with excessive wear or free play” — explained10.8%

    Across all cars, ball joints failures climb 28-fold between three and fifteen years, peaking at 12–14 years. How long ball joints last

  7. 7.Bulbs and lamps

    10.3% of failed tests

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

    • “A lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning” — explained4.8%
    • “Stop lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning” — explained3.5%
    • “Lamp emitted colour, position or intensity not in accordance with the requirements” — explained2.1%

    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

  8. 8.Brake callipers

    9.9% of failed tests

    Pistons and slider pins seize with corrosion and disuse, dragging a brake on or leaving one side weak; shows as imbalance on the roller tester.

    • “Significant brake effort recorded with no brake applied indicating a binding brake” — explained5.7%
    • “Brakes imbalance across an axle such that the braking effort from any wheel is less than 70% of the maximum effort recorded from the other wheel on the same axle.” — explained4.2%

By registration year

TF problems by year

MOT pass rate for MG TF 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.

200270%
200366%−3.3
200469%+2.9
200572%+2.9

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 TF owners about

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

Go deeper

The rest of the TF file

Common questions

What are the most common problems with a MG TF?
Going by what fails the MOT, parking brake (recorded in 25.7% of failed tests), suspension arms and mountings (recorded in 25.3% of failed tests), and catalytic converter and emissions (recorded in 22.4% of failed tests). These are the items testers actually record across 8,683 tests, not reports from owners, so they describe what goes wrong at the point where it has to be fixed.
Which MG TF year is the most reliable?
By MOT pass rate, MG TF cars registered in 2005 do best at 72.2% and 2003 cars do worst at 66.4%. 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 MG TF reliable?
The MG TF passes 69.6% 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 TF?
Start with what fails most: wiper blades and washers, tyres, ball joints. 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