Model Reports 4 min read Updated 18 Oct 2026

MG 3 2015: reliability & common MOT faults

In 2025, 65 in every 100 first MOTs on a 2015 MG 3 were passes. Most common reason for a fail: Airbag warning light.

Summary

A 2015 MG 3 passed first time about 4 in every 100 less often than the average of the 2014 and 2016 model years.

At a glance

How 2,139 first tests went in 2025.

Passed first time
65 in every 100
Did not pass first time
35 in every 100746 failed first-attempt tests
The typical car
10 yearsabout 54,320 miles
First tests counted
2,139

What failed most often

  1. Airbag warning light19 in every 100 failed tests
  2. Suspension arm pins and bushes (front)13 in every 100 failed tests
  3. Tyre condition (front)9 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 2015 MG 3 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.

Seat belts and restraints

One fault: airbag warning light, 23 times as often as on similar cars.

Figures below are measured across the 739 of 746 failed first attempts (99.1%) 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.

Airbag warning light

Failed on 143 first tests23 times as often as similar carsStrong 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.

Suspension

Three faults. The strongest is the suspension sub-frame (front): 18 times as often as on similar cars.

Suspension sub-frame (front)

Failed on 31 first tests18 times as often as similar carsLikely evidence

What it means

A suspension sub-frame insecurely attached to the chassis or axle is Major, and Dangerous when it is insecure and impairing directional stability. A sub-frame that is missing, likely to become detached, fractured or likely to fail is also Dangerous. Excessive damage or corrosion that seriously weakens it is Major.

Also noted as an advisory

Testers also noted it as an advisory, worn but not yet failing, on 83 first tests, 9.2 times as often as on similar cars.

Suspension arm pins and bushes (front)

Failed on 94 first tests2.9 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.

Also noted as an advisory

Testers also noted it as an advisory, worn but not yet failing, on 121 first tests, 2.5 times as often as on similar cars.

Shock absorbers (rear)

Failed on 38 first tests2.9 times as often as similar carsPossible evidence

What it means

Slight seepage that leaves a film of fluid on a shock absorber does not fail it. Severe leakage, or damage so that it does not function, is Major. A shock absorber missing or likely to become detached is graded Dangerous, though a missing one is only rejected if shock absorbers were fitted as standard.

Data: UK MOT open data, 2025. Compared with cars of the same age and mileage. Advisories count notes recorded on failed first tests only.

Brakes

One fault: rigid brake pipes (front), 9.8 times as often as on similar cars.

Rigid brake pipes (front)

Failed on 35 first tests9.8 times as often as similar carsLikely evidence

What it means

Chafing, corrosion or damage to a rigid brake pipe justifies rejection once its wall thickness is reduced by a set amount, although DVSA accepts this is not easy to determine. If a tester is not sure, the benefit of the doubt applies. A leaking pipe or connection is graded Dangerous on a hydraulic system and Major on an air system.

Also noted as an advisory

Testers also noted it as an advisory, worn but not yet failing, on 83 first tests, 7.7 times as often as on similar cars.

Data: UK MOT open data, 2025. Compared with cars of the same age and mileage. Advisories count notes recorded on failed first tests only.

Lamps and electrical

One fault: headlight, 2.4 times as often as on similar cars.

Headlight

Failed on 47 first tests2.4 times as often as similar carsPossible evidence

What it means

On vehicles first used on or after a set date, a halogen headlamp unit converted to take HID or LED bulbs fails for light source and lamp not compatible, which is Major. A complete unit built with those light sources is not failed for that. The precise position of the lamps is not part of the inspection beyond a visual look to see that they sit at about the same height and distance from each side.

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

Noise, emissions and leaks

One fault: petrol engine warning light, 2.1 times as often as on similar cars.

Petrol engine warning light

Failed on 45 first tests2.1 times as often as similar carsPossible evidence

What it means

The malfunction indicator lamp (MIL) on a petrol engine is a Major failure when it is illuminated indicating a malfunction. The detail line DVSA gives for the same row also names an inoperative lamp. The test covers only certain petrol vehicles, depending on their age, size and fuel type.

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. Advisories for the faults above are shown with those faults.

Suspension arm (front)

Noted on 70 first tests17 times as often as similar carsElevated evidence

Rigid brake pipes (rear)

Noted on 43 first tests3.3 times as often as similar carsElevated evidence

Coil spring (rear)

Noted on 75 first tests3.2 times as often as similar carsElevated evidence

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
65in every 100
Passed on the first test.
Fixed at the station
7in 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 65.1% of 2,139 first tests (2025): only cars that passed first time count. Official-style pass 71.9%: cars fixed at the test station also count as a pass. The 7 fixed and the 28 not fixed make the 35 in every 100 that did not pass first time.

Same model, other years

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

406080100201420152016201720182019202020212022Older carsNewer cars
40608010020152020Newer 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, 67 in every 100 passed first time.

YearPassed first timeFirst tests
201467 in every 1001,443
2015 This car65 in every 1002,139
201671 in every 1002,888
201769 in every 1002,714
201872 in every 1002,441
201975 in every 1003,477
202079 in every 1002,366
202182 in every 1001,868
202285 in every 1003,999

FAQs

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

A 2015 MG 3 passed first time about 4 in every 100 less often than the average of the 2014 and 2016 model years. In 2025, 65.1% of 2,139 first MOTs on the 2015 MG 3 passed first time (PRS: items fixed at the station the same day, counted as a fail). The official-style rate including PRS is 71.9%. Among 746 failed first-attempt MOT tests (test year 2025), Airbag warning light appears more often than on similar cars (19.4% of those tests; 143 observed failures; about 23× 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 2015 MG 3 at the first attempt were Airbag warning light (19.4%), Suspension arm pins and bushes (front) (12.7%) and Tyre condition (front) (8.9%), 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: Airbag warning light (19.4% of those tests; 143 observed failures; about 23× more often than similar cars). These are statistical signals, not a diagnosis of any individual car.
Airbag warning light shows up more often than on similar cars (19.4% of those tests; 143 observed failures; about 23× 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 2015 MG 3 include Airbag warning light, Suspension sub-frame (front), Rigid brake pipes (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 2015 MG 3 (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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