The MOT Files

Known faults, from the test record

Mercedes-Benz CLK common problems

What fails on the Mercedes-Benz CLK at MOT, which parts are behind it, and how each model year compares. From 25,027 DVSA test records.

Data updated

Quick answer

The Mercedes-Benz CLK's most common MOT problems are suspension bushes, tyres, coil springs, recorded in 62.0%, 28.9% and 22.5% of failed tests respectively. By model year, 2001 cars pass most often (68.9%) and 2007 cars least (60.5%), 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 Mercedes-Benz CLK 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 25,027 cars.

By component

What wears out on a CLK

Failure items grouped by the part behind them, with the share of failed Mercedes-Benz CLK 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.Suspension bushes

    62.0% 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” — explained24.7%
    • “A suspension joint dust cover missing or no longer prevents the ingress of dirt etc” — explained9.0%
    • “A suspension pin, bush or joint excessively worn” — explained8.8%
    • “A suspension pin, bush or joint excessively worn” — explained4.7%

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

  2. 2.Tyres

    28.9% 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” — explained10.5%
    • “A tyre cords visible or damaged” — explained5.9%
    • “A tyre seriously damaged” — explained5.5%
    • “A tyre seriously damaged” — explained4.8%

    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

  3. 3.Coil springs

    22.5% 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” — explained22.5%

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

  4. 4.Bulbs and lamps

    19.9% 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” — explained5.9%
    • “Stop lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning” — explained4.4%
    • “Product on the lens or light source which obviously reduces light intensity or changes emitted colour to other than white or yellow” — explained3.9%
    • “Lamp emitted colour, position or intensity not in accordance with the requirements” — explained3.1%

    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

  5. 5.Headlamp aim

    17.7% 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” — explained14.9%
    • “The aim of a headlamp is not within limits laid down in the requirements” — explained2.8%

  6. 6.Wiper blades and washers

    13.5% 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” — explained6.4%
    • “Windscreen washers not working or not providing sufficient fluid to clear the windscreen” — explained4.2%
    • “Windscreen washers not working or not providing sufficient fluid to clear the windscreen” — explained2.9%

    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

  7. 7.Brake pipes

    10.3% of failed tests

    Steel pipes under the car corrode from salt and moisture, fastest on cars kept outside in wet or coastal areas; failure is for excessive corrosion or damage.

    • “Brake pipe damaged or excessively corroded” — explained10.3%

    Across all cars, brake pipes failures climb from nothing between three and fifteen years, peaking at 15+ years. How long brake pipes last

  8. 8.Parking brake

    8.7% 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” — explained6.7%
    • “Parking brake efficiency less than 50% of the required value” — explained1.9%

By registration year

CLK problems by year

MOT pass rate for Mercedes-Benz CLK 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.

200169%
200265%−3.4
200366%+0.4
200463%−2.9
200562%−0.7
200662%+0.1
200760%−1.9
200861%+0.3
200961%−0.2

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 CLK owners about

Advisories are the same parts a year or two earlier. Share of all Mercedes-Benz CLK tests carrying an advisory for each.

Go deeper

The rest of the CLK file

Common questions

What are the most common problems with a Mercedes-Benz CLK?
Going by what fails the MOT, suspension bushes (recorded in 62.0% of failed tests), tyres (recorded in 28.9% of failed tests), and coil springs (recorded in 22.5% of failed tests). These are the items testers actually record across 25,027 tests, not reports from owners, so they describe what goes wrong at the point where it has to be fixed.
Which Mercedes-Benz CLK year is the most reliable?
By MOT pass rate, Mercedes-Benz CLK cars registered in 2001 do best at 68.9% and 2007 cars do worst at 60.5%. 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 Mercedes-Benz CLK reliable?
The Mercedes-Benz CLK passes 63.1% 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 Mercedes-Benz CLK?
Start with what fails most: suspension bushes, tyres, coil springs. 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