BMW 3 Series 2020: reliability & common MOT faults

In 2025, 87 in every 100 first MOTs on a 2020 BMW 3 Series were passes. Most common reason for a fail: Tyre condition (front).

Summary

The 2020 BMW 3 Series follows the pattern of the model years either side.

At a glance

How 20,095 first tests went in 2025.

Passed first time
87 in every 100
Did not pass first time
13 in every 1002,607 failed first-attempt tests
The typical car
5 yearsabout 47,391 miles
First tests counted
20,095

What failed most often

  1. Tyre condition (front)26 in every 100 failed tests
  2. Tyre tread depth (rear)13 in every 100 failed tests
  3. Suspension arm ball joint (front)7 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 2020 BMW 3 Series vehicles in 2025, not a prediction that any one car will have them. Faults are grouped by part of the car. A wear pattern follows age and use more than the way the car was built. They come from MOT defect codes, not manufacturer bulletins, recalls or a diagnosis of any one car.

Suspension

One fault: suspension arm ball joint (front), 4.7 times as often as on similar cars.

Figures below are measured across the 2,605 of 2,607 failed first attempts (99.9%) 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.

Suspension arm ball joint (front)

Failed on 176 first tests4.7 times as often as similar carsLikely 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.

Also noted as an advisory

Testers also noted it as an advisory, worn but not yet failing, on 79 first tests, 3.7 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.

Tyres

One wear pattern: tyre tread depth (rear), 3.4 times as often as on similar cars.

Tyre tread depth (rear)

Failed on 341 first tests3.4 times as often as similar carsWear pattern

What it means

Only primary grooves count when tread depth is assessed: those holding the wear indicators, or cut as deep as those when new. Shallower secondary grooves are ignored. Tread depth below the minimum for the vehicle is Dangerous, and so is a pattern not visible over the whole tread, but that second row applies only to vehicles that need the lower minimum.

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

Lamps and electrical

One fault: side repeater indicators, 3.0 times as often as on similar cars.

Side repeater indicators

Failed on 57 first tests3.0 times as often as similar carsLikely evidence

What it means

Sequential or dynamic direction indicators are not a reason to fail. Where a side repeater is required, it is allowed to be part of the front direction indicator if it has a marked wraparound lens, or an amber light coming through the front lens when viewed from a set distance to the side of the rear bumper. A lens defect with no effect on the emitted light is Minor, and one that adversely affects the light is Major.

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

Seat belts and restraints

One fault: seat belt condition (rear), 2.4 times as often as on similar cars.

Seat belt condition (rear)

Failed on 62 first tests2.4 times as often as similar carsPossible evidence

What it means

Any sign of overstretching is a deficiency, and so is a cut anywhere on a child seat belt. On other belts the size of a cut decides it, with a stricter limit at the webbing edge than away from it. Webbing significantly stretched or weakened has rows in both Major and Dangerous grades.

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

Steering

One fault: track rod end (front), 2.0 times as often as on similar cars.

Track rod end (front)

Failed on 66 first tests2.0 times as often as similar carsPossible evidence

What it means

A steering ball joint with excessive wear or free play is Major, and one worn to the extent there is a serious risk of detachment is graded Dangerous. A dust cover that is damaged but still keeps dirt out is Minor, and one missing or no longer keeping dirt out is Major. Testers must tell wear from a joint's built-in clearance or spring loading.

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.

Transmission oil leaks (rear)

Noted on 24 first tests18 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
87in every 100
Passed on the first test.
Fixed at the station
2in every 100
Failed, then fixed at the test station the same day.
Failed
11in every 100
Did not pass, and were not fixed at the test station.

First-attempt pass 87.0% of 20,095 first tests (2025): only cars that passed first time count. Official-style pass 88.6%: cars fixed at the test station also count as a pass. The 2 fixed and the 11 not fixed make the 13 in every 100 that did not pass first time.

By fuel type

First testsTypical mileagePassed first time, as testedPassed first time, same mileage
Hybrid7,79355,309 miles8788
Petrol7,28539,183 miles8786
Diesel3,29050,316 miles8686

Figures are in every 100 first tests. Cars with more miles usually fail more often, so the same-mileage figure gives every fuel the mileage mix of all the cars in this year.

Same model, other years

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

4060801001990199520002005201020152020Older cars
4060801001990200020102020Older 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, 86 in every 100 passed first time.

YearPassed first timeFirst tests
198781 in every 100361
198880 in every 100584
198981 in every 100956
199079 in every 1001,211
199180 in every 100694
199275 in every 100443
199372 in every 100444
199471 in every 100439
199567 in every 100698
199668 in every 1001,034
199770 in every 1001,403
199868 in every 1001,807
199969 in every 1002,275
200066 in every 1002,300
200165 in every 1004,303
200266 in every 1006,585
200367 in every 1008,626
200466 in every 1007,975
200566 in every 1009,502
200667 in every 10015,148
200768 in every 10020,883
200868 in every 10018,398
200967 in every 10019,579
201068 in every 10022,182
201169 in every 10024,338
201268 in every 10030,011
201373 in every 10032,095
201476 in every 10030,147
201579 in every 10030,018
201683 in every 10029,997
201784 in every 10029,056
201886 in every 10023,137
201987 in every 10024,151
2020 This car87 in every 10020,095
202187 in every 10023,580
202285 in every 10012,310

If you are buying one

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

Mileage makes a modest difference on a 2020 BMW 3 Series.

Of 2020 BMW 3 Series vehicles with under 33,000 miles, 89 in every 100 passed their 2025 MOT first time. With 68,000 miles or more, 85 in every 100 did.

Under 33,0004,185 tests
89
33,000–42,0003,695 tests
88
42,000–53,000 Typical car4,211 tests
87
53,000–68,0003,952 tests
87
68,000 and over4,044 tests
85

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 33,00042,000–53,00068,000 and over
Tyre condition (front)3.23.82.9
Tyre tread depth (rear)0.81.92.5
Suspension arm ball joint (front)0.50.61.8
Brake pads (rear)0.80.70.7
Headlight aim0.90.70.7

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


When a car fails

65in every 100

of failed cars had one item to fix.

10in every 100

of failed cars had three or more items to fix.

6in 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 2020 BMW 3 Series follows the pattern of the model years either side. Its main cause of failure was Tyre condition (front), about 26 in every 100 failed tests. In 2025, 87.0% of 20,095 first MOTs on the 2020 BMW 3 Series passed first time (PRS: items fixed at the station the same day, counted as a fail). The official-style rate including PRS is 88.6%. Among 2,607 failed first-attempt MOT tests (test year 2025), Suspension arm ball joint (front) appears more often than on similar cars (6.8% of those tests; 176 observed failures; about 4.7× 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 2020 BMW 3 Series at the first attempt were Tyre condition (front) (26.1%), Tyre tread depth (rear) (13.1%) and Suspension arm ball joint (front) (6.8%), 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: Suspension arm ball joint (front) (6.8% of those tests; 176 observed failures; about 4.7× more often than similar cars). These are statistical signals, not a diagnosis of any individual car.
Suspension arm ball joint (front) shows up more often than on similar cars (6.8% of those tests; 176 observed failures; about 4.7× 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 2020 BMW 3 Series include Suspension arm ball joint (front), Side repeater indicators, Seat belt condition (rear). 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 2020 BMW 3 Series (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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