Model Reports
8 min readUpdated 11 Sep 2026
DVSA open data · 11,474 tests analysed
Fiat 500 2021: reliability & common MOT faults
1,447 first-attempt MOT failures were recorded on the 2021 Fiat 500 in 2025. Figures are among first-attempt failed MOT tests, not among all tests.
Tyres — Condition (front) was the most common reason a 2021 500 failed its MOT — 35.0% of its failed first attempts.
First-attempt pass
87.4%
of 11,474 first tests (2025)
First tests
11,474
test year 2025
Failed first attempts
1,447
failed first-attempt tests
MOT pass rates
First-attempt and official-style rates among class 4 first tests of the year.
First-attempt pass
87.4%
of 11,474 first tests (2025)
Official-style pass
90.9%
incl. same-day PRS fixes
First tests
11,474
class 4 · first MOT of the year
Typical age 4.0 yrs · median mileage 22,073 mi
vs 2024:
-0.9 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 1,447 failed
first attempts in 2025
that the age-and-mileage comparison can be computed on.
Standout: Headlamp (front) — 2.5% of this year's failed first attempts
Recorded on 36 of those tests. It tops the table on elevation — about 2.4× more often than on similar cars of the same age and mileage. That is what makes it unusual for its class, which is a different question from what is most likely to fail; the buying checklist ranks by that. 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
Headlamp (front)
Lamps, reflectors and electrical equipment > Headlamps > Headlamp
Front
36
×2.4
2.5%
Possible
Shock absorbers (rear)
Suspension > Shock absorbers
Rear
31
×2.2
2.1%
Possible
Visibility — Washers
Visibility > Washers
Any
132
×2.0
9.1%
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
Tyre pressure monitoring system
Tyres > Tyre pressure monitoring system
Any
62
×2.1
4.3%
Wear
Tyres — Condition (front)
Tyres > Condition
Front
507
×2.0
35.0%
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
Shock absorbers (rear)
Suspension > Shock absorbers
Rear
39
×3.7
2.7%
Possible
Shock absorbers (front)
Suspension > Shock absorbers
Front
32
×2.2
2.2%
Elevated
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.
Nothing separates this year from the 500 either side of it, so buy on the individual car. The checks below are the items that actually failed 2021 500, commonest first.
What to check on a 2021 500
The items that failed 2021 500 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.
Tyres — Condition (front) — recorded on 35.0% of failed first attempts
Visibility — Washers — recorded on 9.1% of failed first attempts
Tread depth (front) — recorded on 8.4% of failed first attempts
Visibility — Wipers (front) — recorded on 7.4% of failed first attempts
Headlamp aim — recorded on 6.6% 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.
Tyres — Condition (front) was the most common reason a 2021 500 failed its MOT — 35.0% of its failed first attempts. In 2025, 87.4% of 11,474 first MOTs on the 2021 Fiat 500 passed first time (PRS — items fixed at the station the same day — counted as a fail). The official-style rate including PRS is 90.9%. Among 1,447 failed first-attempt MOT tests (test year 2025), Headlamp (front) appears more often than on simil…
Ranked by how often they were actually recorded, the items that failed 2021 Fiat 500s most often at the first attempt were Tyres — Condition (front) (35.0%), Visibility — Washers (9.1%) and Tread depth (front) (8.4%) — 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: Headlamp (front) (2.5% of those tests; 36 observed failures; about 2.4× more often than similar cars). These are statistical signals, not a diagnosis of any individual car.
Headlamp (front) shows up more often than on similar cars (2.5% of those tests; 36 observed failures; about 2.4× 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 2021 Fiat 500 include Headlamp (front), Shock absorbers (rear), Visibility — Washers. 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 2021 Fiat 500 (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.
20242025
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.