Model Reports 8 min read Updated 11 Sep 2026 DVSA open data · 2,161 tests analysed

Mercedes-Benz Sl 2003: reliability & common MOT faults

405 first-attempt MOT failures were recorded on the 2003 Mercedes-Benz Sl in 2025. Figures are among first-attempt failed MOT tests, not among all tests.

First-attempt pass rate 81.3% across 2,161 tests in 2025. Nothing in this year's figures separates it from the Sls either side — no fuel gap, and no break in the model's own trend.

First-attempt pass

81.3%

of 2,161 first tests (2025)

First tests

2,161

test year 2025

Failed first attempts

405

failed first-attempt tests

MOT pass rates

First-attempt and official-style rates among class 4 first tests of the year.

First-attempt pass

81.3%

of 2,161 first tests (2025)

Official-style pass

83.8%

incl. same-day PRS fixes

First tests

2,161

class 4 · first MOT of the year

Typical age 22.0 yrs · median mileage 73,824 mi

vs 2024: +1.8 pp first-attempt

Note:

  • Class 4 cars · first MOT of the year per vehicle · P/PRS/F outcomes (2025 data).
  • PRS (fixed at the station the same day) counts as a fail in the first-attempt rate.
  • Raw outcomes for this cohort — not adjusted for age, mileage, or peer mix.
  • MOT doesn't test engine or gearbox internals.

Common faults

Failure patterns that show up more often on this registration year than on similar cars.

These MOT failure patterns show up more often on this registration year than on similar cars of the same class, age, and mileage.

Shares below are measured across the 401 of 405 failed first attempts (99.0%) that recorded an odometer reading in 2025 — the subset the age-and-mileage comparison can be computed on.

Standout: SRS malfunction indicator lamp — 9.2% of this year's failed first attempts

Recorded on 37 of those tests. It tops the table on elevation — about 3.2× more often than on similar cars of the same age and mileage. The full ranked list is in the table below.

No patterns met the strongest callout thresholds on this page; showing the highest-lift rows that still cleared the display floors.

Fault pattern Location Failures vs similar cars Share of fails Confidence
SRS malfunction indicator lamp
Seat belts and supplementary restraint systems > SRS malfunction indicator lamp
 Any 37 ×3.2 9.2% Likely
Ball joint dust cover (front)
Suspension > Suspension arms > Ball joint dust cover
 Front 24 ×2.5 6.0% Possible
Rigid brake pipes (front)
Brakes > Rigid brake pipes
 Front 21 ×2.2 5.2% Possible

Only patterns that clear minimum sample and elevation thresholds are shown (at least 20 failures and about 2.0× more often than similar cars).

Note: Rates and comparisons are among first-attempt failed tests, not all MOTs. Patterns come from MOT defect codes — not manufacturer service bulletins, recalls, or a diagnosis of any individual car. Failures and advisories are listed separately.

Wear patterns

Usage and mileage effects that often track road use rather than model design.

These patterns look like wear or usage effects rather than model-specific design faults. Tyres, brake friction material, and alignment-related defects often track mileage and road use.

Pattern Location Failures vs similar cars Share of fails Confidence
Tyres — Condition (rear)
Tyres > Condition
 Rear 45 ×2.5 11.2% Wear
Tyres — Condition (front)
Tyres > Condition
 Front 45 ×2.2 11.2% Wear
Note: These patterns are not treated as a model design fault in our common-faults ranking.

Advisories

Notes recorded at the test that appear more often than on similar cars.

Advisory notes recorded on failed first-attempt tests that appear more often than on similar cars.

Advisory pattern Location Notes vs similar cars Share Confidence
Wheel bearings (front)
Suspension > Wheel bearings
 Front 27 ×4.4 6.7% Elevated
Ball joint (front)
Suspension > Suspension arms > Ball joint
 Front 35 ×4.0 8.7% Elevated
Flexible brake hoses (rear)
Brakes > Flexible brake hoses
 Rear 27 ×2.1 6.7% Elevated
Note: Advisories are not a fail rate — they flag issues noted at the test, often before they become failures.

FAQs

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

Nothing in this year's figures separates it from the Sls either side — no fuel gap, and no break in the model's own trend. In 2025, 81.3% of 2,161 first MOTs on the 2003 Mercedes-Benz Sl passed first time (PRS — items fixed at the station the same day — counted as a fail). The official-style rate including PRS is 83.8%. Among 405 failed first-attempt MOT tests (test year 2025), SRS malfunction indicator lamp appears…
Among failed first-attempt tests we highlight patterns that appear more often than on similar cars. Top example: SRS malfunction indicator lamp (9.2% of those tests; 37 observed failures; about 3.2× more often than similar cars). These are statistical signals, not a diagnosis of any individual car.
SRS malfunction indicator lamp shows up more often than on similar cars (9.2% of those tests; 37 observed failures; about 3.2× 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 check point, not a manufacturer service bulletin.
Common MOT problem areas for the 2003 Mercedes-Benz Sl include SRS malfunction indicator lamp, Ball joint dust cover (front), Rigid brake pipes (front). These patterns show up more often than on similar cars after we filter out sparse noise — not a full list of every possible fault on an 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 Sl (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.
  • We never invent pass rates, star scores, or ranks when those data marts are missing.

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

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