Model Reports 4 min read Updated 18 Oct 2026

Mercedes-Benz CLK 2003: reliability & common MOT faults

In 2025, 66 in every 100 first MOTs on a 2003 Mercedes-Benz CLK were passes. Most common reason for a fail: Suspension arm ball joint (front).

Summary

The 2003 Mercedes-Benz CLK follows the pattern of the model years either side.

At a glance

How 2,340 first tests went in 2025.

Passed first time
66 in every 100
Did not pass first time
34 in every 100806 failed first-attempt tests
The typical car
22 yearsabout 102,720 miles
First tests counted
2,340

What failed most often

  1. Suspension arm ball joint (front)13 in every 100 failed tests
  2. Coil spring (front)12 in every 100 failed tests
  3. Airbag warning light10 in every 100 failed tests

How we count this. Data: UK MOT open data, 2025. Only Class 4 cars on their first MOT of the year are counted. A car that fails and is fixed at the test station still counts as a fail in the first-attempt rate. These are raw results, not adjusted for age, mileage, or peer mix. The MOT does not test engine or gearbox internals.

Note:

These are patterns across 2003 Mercedes-Benz CLK vehicles in 2025, not a prediction that any one car will have them. Faults are grouped by part of the car. They come from MOT defect codes, not manufacturer bulletins, recalls or a diagnosis of any one car.

Suspension

Three faults. The strongest is the coil spring (front): 4.3 times as often as on similar cars.

Figures below are measured across the 791 of 806 failed first attempts (98.1%) that recorded an odometer reading in 2025. Mileage is needed to compare like with like.

We only list faults with at least 20 failures and a rate of about 2.0 times that of similar cars, which keeps one-off results out of the list.

Coil spring (front)

Failed on 95 first tests4.3 times as often as similar carsLikely evidence

What it means

A missing bump stop rubber is not a reason to fail a coil spring. When the vehicle is jacked and lowered, a spring that does not correctly locate as the suspension returns to its normal running position is rejected as insecurely attached. A missing spring is Major, and graded Dangerous where directional control is affected.

Suspension arm ball joint (front)

Failed on 101 first tests2.5 times as often as similar carsPossible evidence

What it means

A suspension arm ball joint is failed under the general suspension pin, bush or joint wording. Excessively worn is Major, and likely to become detached is graded Dangerous.

Suspension arm pins and bushes (front)

Failed on 60 first tests2.0 times as often as similar carsPossible evidence

What it means

Pins and bushes on suspension arms fail as Major when they are excessively worn. They are graded Dangerous when likely to become detached. DVSA uses the same wording for a suspension joint.

Data: UK MOT open data, 2025. Compared with cars of the same age and mileage.

Seat belts and restraints

One fault: airbag warning light, 3.5 times as often as on similar cars.

Airbag warning light

Failed on 83 first tests3.5 times as often as similar carsLikely evidence

What it means

The airbag warning lamp (SRS MIL in DVSA's wording) is failed only if it indicates a system malfunction, which is Major. A lamp lit to show the passenger airbag is disabled is not to be regarded as a defect. Dashboard messages are not a defect in their own right, though they can help the tester confirm a malfunction.

Data: UK MOT open data, 2025. Compared with cars of the same age and mileage.

Advisories

Other things testers noted as worn or close to failing, more often than on similar cars.

An advisory is a note from the tester about something that has not failed yet. It is an early warning, not a fail.

Anti-roll bar (rear)

Noted on 36 first tests8.7 times as often as similar carsElevated evidence

Wheel bearings (front)

Noted on 74 first tests5.2 times as often as similar carsElevated evidence

Flexible brake hoses (rear)

Noted on 69 first tests2.5 times as often as similar carsElevated evidence

Suspension sub-frame (rear)

Noted on 85 first tests2.1 times as often as similar carsElevated evidence

Transmission oil leaks

Noted on 29 first tests2.0 times as often as similar carsElevated evidence

Brake pads (rear)

Noted on 42 first tests2.0 times as often as similar carsWear pattern

Data: UK MOT open data, 2025. Counts cover advisories recorded on failed first tests only, compared with cars of the same age and mileage.

MOT pass rates

How first tests ended, and how the pass rates are counted.

Passed first time
66in every 100
Passed on the first test.
Fixed at the station
6in every 100
Failed, then fixed at the test station the same day.
Failed
28in every 100
Did not pass, and were not fixed at the test station.

First-attempt pass 65.6% of 2,340 first tests (2025): only cars that passed first time count. Official-style pass 72.1%: cars fixed at the test station also count as a pass. The 6 fixed and the 28 not fixed make the 34 in every 100 that did not pass first time.

Same model, other years

Passed first time in every 100, all tested in 2025.

40608010020002003Older carsNewer cars
40608010020002003Older carsNewer cars

Newer cars are younger, so look for a jump rather than the climb. A year earlier (2024), when these cars were a year younger, 63 in every 100 passed first time.

YearPassed first timeFirst tests
199968 in every 100662
200071 in every 100903
200169 in every 1001,084
200265 in every 1001,275
2003 This car66 in every 1002,340
200463 in every 1003,267
200562 in every 1003,244
200662 in every 1002,701
200760 in every 1003,214
200860 in every 1002,315
200960 in every 1002,614

If you are buying one

What this year's MOT record means for the decision in front of you.

Mileage matters most on a 2003 Mercedes-Benz CLK.

Of 2003 Mercedes-Benz CLK vehicles with under 71,000 miles, 76 in every 100 passed their 2025 MOT first time. With 134,000 miles or more, 59 in every 100 did.

Under 71,000460 tests
76
71,000–94,000476 tests
64
94,000–112,000 Typical car458 tests
66
112,000–134,000449 tests
63
134,000 and over471 tests
59

What to check at your mileage

How often each fault turned up on a failed first test, by the car's mileage. Read it as: what is likely to need looking at on a car like the one in front of you.

Under 71,00094,000–112,000134,000 and over
Suspension arm ball joint (front)0.76.16.6
Coil spring (front)3.04.43.8
Airbag warning light2.64.14.2
Headlight aim1.13.15.1
Tyre condition (front)3.02.42.8

Faults per 100 first tests, by the car's mileage at the test.

When a car fails

26in every 100

of failed cars had one item to fix.

50in every 100

of failed cars had three or more items to fix.

8in every 100

of all first tests had a defect the tester marked dangerous (unsafe to drive away).

Every figure here is a first-attempt MOT rate from DVSA open data for this model line, for cars of this model year tested in 2025. Each mileage band holds a fifth of the tests. MOTs do not test engine or gearbox internals, so this is a pre-purchase checklist, not a full reliability score.

FAQs

Short answers about how to read this model-year guide.

The 2003 Mercedes-Benz CLK follows the pattern of the model years either side. Its main cause of failure was Suspension arm ball joint (front), about 13 in every 100 failed tests. In 2025, 65.6% of 2,340 first MOTs on the 2003 Mercedes-Benz CLK passed first time (PRS: items fixed at the station the same day, counted as a fail). The official-style rate including PRS is 72.1%. Among 806 failed first-attempt MOT tests (test year 2025), Coil spring (front) appears more often than on similar cars (12.0% of those tests; 95 observed failures; about 4.3× more often than similar cars). There is no single reliability score here; this is a pre-purchase checklist built from DVSA open data, not a guarantee for any individual car.
Ranked by how often they were actually recorded, the items that most often failed a 2003 Mercedes-Benz CLK at the first attempt were Suspension arm ball joint (front) (12.8%), Coil spring (front) (12.0%) and Airbag warning light (10.5%), each as a share of the year's failed first attempts. That is what goes wrong most often on the car. The common faults table shows a different measure: faults that are unusual compared with similar cars.
Among failed first-attempt tests we highlight patterns that appear more often than on similar cars. Top example: Coil spring (front) (12.0% of those tests; 95 observed failures; about 4.3× more often than similar cars). These are statistical signals, not a diagnosis of any individual car.
Coil spring (front) shows up more often than on similar cars (12.0% of those tests; 95 observed failures; about 4.3× more often than similar cars). That does not prove a design fault. Age, mileage, and how the car was used still matter. Treat it as a pre-purchase checkpoint, not a manufacturer service bulletin.
Common MOT problem areas for the 2003 Mercedes-Benz CLK include Coil spring (front), Airbag warning light, Suspension arm ball joint (front). These are the faults that stand out compared with similar cars, not a complete list of what can go wrong on any individual car.
Advisories flag issues noted at the test and are not a fail rate. We show advisory patterns that appear more often than on similar cars among failed first-attempt tests, separate from common failure rows. Use them as early-warning checks, not as a pass/fail score.
This page highlights MOT failure patterns for the 2003 Mercedes-Benz CLK (registration year) using UK DVSA open data for the selected test year. Patterns are compared with cars of a similar age and mileage. It is a buyer checklist from MOT defect statistics, not a full service history or manufacturer service-bulletin list.
No. MOT tests do not cover engine internals, gearboxes, or many electronic modules. Patterns here come from MOT defect statistics only and should not be read as engine or gearbox reliability scores.

About this data

How this page is built and what it can (and can't) say.

These figures come from UK MOT open data for this model year. We surface common failure patterns against similar cars, not a full reliability score, and not a pass/fail verdict on any individual vehicle.

2024 2025

What we include

UK Class 4 cars only. Normal MOT tests (not retests); first test per vehicle per calendar year; results pass, PRS, or fail.

Same-day repairs

PRS means the car failed items that were fixed at the test station and then passed the same day. We count PRS as a first-attempt fail in headline rates so same-day repairs do not hide problems.

How we compare

We compare this model year with other Class 4 cars of similar age and mileage in the same test year. This model family is left out of the peer group so the car is not measured against itself.

What this does not cover

  • MOTs do not cover engine internals, gearboxes, or many electronics; this is not a full reliability score.
  • Common faults come from MOT defect stats, not manufacturer TSBs or recalls.
  • Age and mileage matching reduces, but does not remove, differences in how cars were used and maintained.
  • If the data for a car is too thin to say anything useful, we say so rather than guess.

Contains public sector information licensed under the Open Government Licence v3.0.

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