BMW 420 Reliability: Common Problems and Years to Avoid
What the BMW 420 fails its MOT on, with rough repair costs, and how each model year's MOT pass rate compares with other cars of the same age. Based on 141,320 MOT tests across 9 model years (DVSA data for tests carried out in 2024, retests included).
Segment: premium | Fuel: Diesel, Petrol
89%
BMW 420 pass rate
88%
BMW average
82%
All-model average
The BMW 420 has an average MOT pass rate of 89%, which is 1 point above the BMW average and 7 points above the average across all models in our data. Newer BMW 420s pass their MOT more often than older ones, by 4 percentage points on average, which is mostly down to age and wear.
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What the BMW 420 Fails Its MOT On
Of the 10,949 MOT tests on the BMW 420 that failed at the first attempt in 2025, the share that failed on each part of the test, next to the share for all cars and vans of the same ages. A test that failed on two areas counts in both.
Tyres
47%Cars and vans the same age: 27% (the 420 fails on this more often) · Typical repair £50-£300
Lights and electrics
21%Cars and vans the same age: 30% (the 420 fails on this less often) · Typical repair £15-£200
Suspension
17%Cars and vans the same age: 26% (the 420 fails on this less often) · Typical repair £150-£600
Brakes
16%Cars and vans the same age: 20% · Typical repair £80-£450
Windscreen, wipers and mirrors
13%Cars and vans the same age: 15% · Typical repair £10-£350
The 3 single faults it failed on most
- Tyre has ply or cords exposed (13% of failed tests, tyres)
- Tyre tread depth below the 1.6mm limit (13% of failed tests, tyres)
- Tyre has a cut deep enough to reach the ply or cords (11% of failed tests, tyres)
Source: CarCostCheck analysis of DVSA anonymised MOT test results and failure items for 2025: first attempt at each MOT, fail and pass-after-repair defects, DVSA's defect categories (names shortened). Repair costs are rough UK ranges, not quotes. Method and national figures: MOT failure reasons 2025.
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BMW 420 Years to Avoid
Every car in the 2024 MOT data was tested at the same age as the other cars first registered that year, so each 420 year is compared with all cars from the same year. Years with 1,000+ tests that were at least three years old are included.
Failed more often than cars their age
No year passed 3 or more points less often than other cars of the same age.
A lower pass rate means that year failed its MOT more often in 2024; it does not mean every car from that year is bad. Old cars still on the road are often the best-kept ones, which can lift the pass rates of the oldest years. How a car has been looked after matters more, so check the MOT history of the car you are looking at.
BMW 420 Reliability by Year
MOT pass rate for each model year, from DVSA data for tests carried out in 2024 (retests included). Newer cars usually pass more often simply because they are younger. All Cars is the pass rate of every car first registered that year, with the gap in points. Highest and lowest are marked among years with 100+ tests that were at least three years old when tested. Fuel and engine size are a guide only.
BMW 420 Running Costs
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BMW 420 FAQ
What are the most common BMW 420 problems?
In 2025, MOT tests on the BMW 420 that failed at the first attempt most often failed on tyres (47% of the 10,949 failed tests), lights and electrics (21%) and suspension (17%). The single most common fault was "Tyre has ply or cords exposed" (13%). Across 141,320 MOT tests (DVSA MOT data for tests in 2024, retests included), 89% ended in a pass.
Is the BMW 420 reliable?
The BMW 420 has an average MOT pass rate of 89%, from 141,320 MOT tests (DVSA MOT data for tests in 2024, retests included). Comparing each model year with all cars first registered the same year, so that age is allowed for, it passed 3 points more often on average, a better than average result for its age.
Which BMW 420 years should I avoid?
No BMW 420 year with 1,000+ tests passed 3 or more points less often than all cars first registered the same year (DVSA MOT data for tests in 2024, retests included). The years that passed most often for their age were the 2013 (85% of 1,309 tests passed, against 80% for all 2013 cars), the 2015 (88% of 23,559 tests passed, against 84% for all 2015 cars) and the 2014 (86% of 18,990 tests passed, against 82% for all 2014 cars). A year's pass rate does not tell you about one car, so check the MOT history of the car you are buying.
How much does it cost to fix common BMW 420 faults?
As a rough guide, brake work on a BMW 420 typically costs £80-£450 and suspension repairs £150-£600, while exhaust and emissions fixes can cost £80-£800. Lighting and wiper fixes are usually under £200.
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Other BMW Models
Common problems pages for other BMW models