Kia Niro 2018: reliability & common MOT faults

In 2025, 86 in every 100 first MOTs on a 2018 Kia Niro were passes. Most common reason for a fail: Tyre condition (rear).

Summary

The 2018 Kia Niro follows the pattern of the model years either side.

At a glance

How 6,079 first tests went in 2025.

Passed first time
86 in every 100
Did not pass first time
14 in every 100880 failed first-attempt tests
The typical car
7 yearsabout 59,922 miles
First tests counted
6,079

What failed most often

  1. Tyre condition (rear)17 in every 100 failed tests
  2. Tyre tread depth (front)8 in every 100 failed tests
  3. Windscreen wipers (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 2018 Kia Niro 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.

Brakes

Three faults. The strongest is the brake efficiency below minimum (roller test): 16 times as often as on similar cars.

Figures below are measured across the 879 of 880 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.

Brake efficiency below minimum (roller test)

Failed on 51 first tests16 times as often as similar carsLikely evidence

What it means

Service brake efficiency below the minimum requirement is Major, and efficiency less than half of the required value is graded Dangerous. On a roller brake tester, if more than half of the wheels of a brake system lock, the efficiency requirement for that system counts as met.

Brake performance (roller test, rear)

Failed on 24 first tests2.4 times as often as similar carsPossible evidence

What it means

A wheel with no recorded braking effort on the roller test is graded Dangerous. Inadequate effort, a brake grabbing severely, abnormal lag and excessive fluctuation in effort are each Major. So is significant brake effort recorded with no brake applied, which indicates a binding brake.

Also noted as an advisory

Testers also noted it as an advisory, worn but not yet failing, on 28 first tests, 2.8 times as often as on similar cars.

Handbrake efficiency below minimum (roller test)

Failed on 40 first tests2.2 times as often as similar carsPossible evidence

What it means

A parking brake with efficiency below the minimum requirement is Major, and graded Dangerous where efficiency is less than half of the required value. On a roller brake tester, the requirement counts as met if more than half of the wheels of a brake system lock. The check applies only to vehicles whose parking brake was not already tested as the secondary brake.

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

Two faults. The strongest is the side repeater indicators: 3.6 times as often as on similar cars.

Side repeater indicators

Failed on 36 first tests3.6 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.

Number plate lights (rear)

Failed on 30 first tests2.3 times as often as similar carsPossible evidence

What it means

Registration plate lamps must light up the rear registration plate and operate at the same time as the position lamps. A missing or inoperative lamp is Major when the plate has only one lamp or all its lamps are not working, and Minor when the plate has several lamps or light sources and not all have failed. A lamp throwing direct white light to the rear is also Minor.

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

Tyres

One wear pattern: tyre condition (rear), 2.0 times as often as on similar cars.

Tyre condition (rear)

Failed on 153 first tests2.0 times as often as similar carsWear pattern

What it means

Exposed or damaged ply or cords are graded Dangerous. A cut in excess of the requirements and deep enough to reach the ply or cords is Major, and testers may open the cut with a blunt instrument to check its depth. A tyre contacting the vehicle through flexing or suspension movement is not a defect; fouling fails only at the time of test.

Data: UK MOT open data, 2025. 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
86in every 100
Passed on the first test.
Fixed at the station
3in 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 85.5% of 6,079 first tests (2025): only cars that passed first time count. Official-style pass 88.9%: cars fixed at the test station also count as a pass. The 3 fixed and the 11 not fixed make the 14 in every 100 that did not pass first time.

Same model, other years

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

4060801002016201720182019202020212022Older carsNewer cars
4060801002018Older carsNewer 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, 85 in every 100 passed first time.

YearPassed first timeFirst tests
201684 in every 1001,188
201784 in every 1004,067
2018 This car86 in every 1006,079
201986 in every 1008,770
202086 in every 10017,538
202187 in every 10022,687
202288 in every 10022,596

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 2018 Niro.

Of 2018 Niro vehicles with under 39,000 miles, 89 in every 100 passed their 2025 MOT first time. With 97,000 miles or more, 83 in every 100 did.

Under 39,0001,215 tests
89
39,000–53,0001,225 tests
86
53,000–68,000 Typical car1,208 tests
85
68,000–97,0001,208 tests
85
97,000 and over1,222 tests
83

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 39,00053,000–68,00097,000 and over
Tyre condition (rear)3.42.70.9
Tyre tread depth (front)0.51.31.2
Windscreen wipers (front)1.20.70.9
Brake pads (rear)0.21.21.1
Brake efficiency below minimum (roller test)0.20.91.1

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


When a car fails

59in every 100

of failed cars had one item to fix.

14in every 100

of failed cars had three or more items to fix.

5in 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 2018 Kia Niro follows the pattern of the model years either side. Its main cause of failure was Tyre condition (rear), about 17 in every 100 failed tests. In 2025, 85.5% of 6,079 first MOTs on the 2018 Kia Niro passed first time (PRS: items fixed at the station the same day, counted as a fail). The official-style rate including PRS is 88.9%. Among 880 failed first-attempt MOT tests (test year 2025), Brake efficiency below minimum (roller test) appears more often than on similar cars (5.8% of those tests; 51 observed failures; about 16× 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 2018 Kia Niro at the first attempt were Tyre condition (rear) (17.4%), Tyre tread depth (front) (8.2%) and Windscreen wipers (front) (6.9%), 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: Brake efficiency below minimum (roller test) (5.8% of those tests; 51 observed failures; about 16× more often than similar cars). These are statistical signals, not a diagnosis of any individual car.
Brake efficiency below minimum (roller test) shows up more often than on similar cars (5.8% of those tests; 51 observed failures; about 16× 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 2018 Kia Niro include Brake efficiency below minimum (roller test), Side repeater indicators, Brake performance (roller test, 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.
This page highlights MOT failure patterns for the 2018 Kia Niro (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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