Model Reports 8 min read Updated 11 Sep 2026 DVSA open data · 5,097 tests analysed

Mercedes-Benz A-Class 2011: reliability & common MOT faults

1,735 first-attempt MOT failures were recorded on the 2011 Mercedes-Benz A-Class in 2025. The items recorded most often on them were Side repeaters and Headlamp aim. Figures are among first-attempt failed MOT tests, not among all tests.

Petrol A-Class passed first time 3.3 pp more often than diesel ones (67.1% of 3,369 vs 63.8% of 1,728).

First-attempt pass

66.0%

of 5,097 first tests (2025)

First tests

5,097

test year 2025

Failed first attempts

1,735

failed first-attempt tests

Most common fail

11.2%

Side repeaters

MOT pass rates

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

First-attempt pass

66.0%

of 5,097 first tests (2025)

Official-style pass

72.2%

incl. same-day PRS fixes

First tests

5,097

class 4 · first MOT of the year

Typical age 14.0 yrs · median mileage 71,816 mi

vs 2024: +0.4 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 1,734 of 1,735 failed first attempts (99.9%) that recorded an odometer reading in 2025 — the subset the age-and-mileage comparison can be computed on.

Standout: Side repeaters (front) — 11.2% of this year's failed first attempts

Recorded on 195 of those tests. It tops the table on elevation — about 8.0× more often than on similar cars of the same age and mileage. On this year it is also the commonest failure, so it answers both questions at once. The full ranked list is in the table below.

Fault pattern Location Failures vs similar cars Share of fails Confidence
Side repeaters (front)
Lamps, reflectors and electrical equipment > Direction indicators > Flashing type > Side repeaters
 Front 195 ×8.0 11.2% Strong
Service brake performance
Brakes > Brake performance > Service Brake Efficiency (sp) > Rbt (sp) > Service brake performance
 Any 107 ×6.9 6.2% Strong
Electrical equipment — Horn
Lamps, reflectors and electrical equipment > Electrical equipment > Horn
 Any 114 ×6.2 6.6% Strong
Rigid brake pipes (rear)
Brakes > Rigid brake pipes
 Rear 109 ×4.0 6.3% Likely
Malfunction indicator lamp
Noise, emissions and leaks > Exhaust emissions > Spark ignition > Malfunction indicator lamp
 Any 142 ×3.0 8.2% Likely
Malfunction indicator lamp
Noise, emissions and leaks > Exhaust emissions > Compression ignition > Malfunction indicator lamp
 Any 61 ×2.9 3.5% Possible
Shock absorbers (front)
Suspension > Shock absorbers
 Front 107 ×2.8 6.2% Possible
Visibility — Washers (front)
Visibility > Washers
 Front 97 ×2.1 5.6% 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.

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
Rigid brake pipes (rear)
Brakes > Rigid brake pipes
 Rear 288 ×4.2 16.6% Likely
Rigid brake pipes (front)
Brakes > Rigid brake pipes
 Front 153 ×3.5 8.8% Possible
Note: Advisories are not a fail rate — they flag issues noted at the test, often before they become failures.

If you are buying one

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

On this year, prefer the petrol. The diesel cars passed first time 3.3 pp less often, on 1,728 tests.

What to check on a 2011 A-Class

The items that failed 2011 A-Class most often, as a share of the year's failed first attempts. This is what goes wrong, not what is unusual — the table further up the page covers that.

  • Side repeaters — recorded on 11.2% of failed first attempts
  • Headlamp aim — recorded on 10.3% of failed first attempts
  • Ball joint (front) — recorded on 9.8% of failed first attempts
  • Visibility — Washers — recorded on 9.5% of failed first attempts
  • Malfunction indicator lamp — recorded on 8.2% of failed first attempts

Every figure here is a first-attempt MOT rate from DVSA open data for this model line. 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.

Petrol A-Class passed first time 3.3 pp more often than diesel ones (67.1% of 3,369 vs 63.8% of 1,728). In 2025, 66.0% of 5,097 first MOTs on the 2011 Mercedes-Benz A-Class passed first time (PRS — items fixed at the station the same day — counted as a fail). The official-style rate including PRS is 72.2%. Among 1,735 failed first-attempt MOT tests (test year 2025), Side repeaters (front) appears more often than on…
Ranked by how often they were actually recorded, the items that failed 2011 Mercedes-Benz A-Classs most often at the first attempt were Side repeaters (11.2%), Headlamp aim (10.3%) and Ball joint (front) (9.8%) — each as a share of the year's failed first attempts. That is what goes wrong on the car. It is a different question from which patterns are unusual for the class, which the common-faults table answers.
Among failed first-attempt tests we highlight patterns that appear more often than on similar cars. Top example: Side repeaters (front) (11.2% of those tests; 195 observed failures; about 8.0× more often than similar cars). These are statistical signals, not a diagnosis of any individual car.
Side repeaters (front) shows up more often than on similar cars (11.2% of those tests; 195 observed failures; about 8.0× 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 2011 Mercedes-Benz A-Class include Side repeaters (front), Service brake performance, Electrical equipment — Horn. 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 2011 Mercedes-Benz A-Class (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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