Model Reports 4 min read Updated 18 Oct 2026

Mercedes-Benz Citan 2018: reliability & common MOT faults

In 2025, 62 in every 100 first MOTs on a 2018 Mercedes-Benz Citan were passes. Most common reason for a fail: Brake light.

Summary

The 2018 Mercedes-Benz Citan follows the pattern of the model years either side.

At a glance

How 3,388 first tests went in 2025.

Passed first time
62 in every 100
Did not pass first time
38 in every 1001,298 failed first-attempt tests
The typical car
7 yearsabout 89,039 miles
First tests counted
3,388

What failed most often

  1. Brake light15 in every 100 failed tests
  2. Individual sidelight or tail light (front)15 in every 100 failed tests
  3. Drive shaft joints and boots (front)14 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 Mercedes-Benz Citan 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.

Lamps and electrical

Four faults. The strongest is the brake light (rear): 5.4 times as often as on similar cars.

Figures below are measured across the 1,294 of 1,298 failed first attempts (99.7%) 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 light (rear)

Failed on 194 first tests5.4 times as often as similar carsStrong evidence

What it means

All stop lamps missing or not working is graded Dangerous, and so is a stop lamp that stays on when the brakes are released. A stop lamp that is missing or not working is Major. On some vehicles with LED rear lamps, part of the stop lamp can go out when the rear fog lamp is lit, which is not regarded as a defect.

Also noted as an advisory

Testers also noted it as an advisory, worn but not yet failing, on 44 first tests, 8.5 times as often as on similar cars.

Individual sidelight or tail light (front)

Failed on 192 first tests4.1 times as often as similar carsLikely evidence

What it means

A position lamp showing red light to the front or white light to the rear is Major. Rear lamps must show a steady red light, and front ones can show white, predominantly white with a blue tinge, or yellow if combined in a yellow headlamp. With a multiple light source, up to half not working is Minor and more than half is Major.

Number plate lights (rear)

Failed on 118 first tests2.7 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.

Rear fog light

Failed on 26 first tests2.5 times as often as similar carsPossible evidence

What it means

A missing obligatory rear fog lamp, one that is not working, or one that does not emit a steady red light is graded Major. A rear fog lamp adversely affected by the operation of any other lamp is Major too. The manual allows it to go out when main beam is switched on or when dipped beam headlamps are switched off.

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

Body and structure

One fault: drive shaft joints and boots (front), 4.2 times as often as on similar cars.

Drive shaft joints and boots (front)

Failed on 183 first tests4.2 times as often as similar carsLikely evidence

What it means

A constant velocity boot that is only severely deteriorated is Minor. It is Major once it is missing, split or insecure so that it no longer prevents the ingress of dirt. A transmission joint excessively worn is Major, and graded Dangerous when it is so worn it is likely to fail.

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

Steering

One fault: track rod end (front), 2.1 times as often as on similar cars.

Track rod end (front)

Failed on 81 first tests2.1 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.

Also noted as an advisory

Testers also noted it as an advisory, worn but not yet failing, on 29 first tests, 3.4 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.

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.

Brake pedal

Noted on 33 first tests7.9 times as often as similar carsElevated evidence

Rigid brake pipes (rear)

Noted on 62 first tests3.8 times as often as similar carsElevated evidence

Wheel condition (front)

Noted on 35 first tests3.3 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
62in every 100
Passed on the first test.
Fixed at the station
10in 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 61.7% of 3,388 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 10 fixed and the 28 not fixed make the 38 in every 100 that did not pass first time.

Same model, other years

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

406080100201320142015201620172018201920202021Older 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, 63 in every 100 passed first time.

YearPassed first timeFirst tests
201351 in every 1001,326
201453 in every 1001,910
201557 in every 1002,254
201658 in every 1003,149
201760 in every 1003,084
2018 This car62 in every 1003,388
201965 in every 1001,853
202069 in every 1001,287
202171 in every 100956

If you are buying one

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

Mileage matters most on a 2018 Citan.

Of 2018 Citan vehicles with under 60,000 miles, 71 in every 100 passed their 2025 MOT first time. With 125,000 miles or more, 60 in every 100 did.

Under 60,000676 tests
71
60,000–81,000689 tests
65
81,000–98,000 Typical car648 tests
59
98,000–125,000695 tests
55
125,000 and over673 tests
60

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 60,00081,000–98,000125,000 and over
Brake light5.36.34.8
Individual sidelight or tail light (front)1.05.99.1
Drive shaft joints and boots (front)4.36.33.3
Tyre tread depth (front)1.64.23.9
Brake pads (rear)2.55.24.3

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

When a car fails

28in every 100

of failed cars had one item to fix.

43in every 100

of failed cars had three or more items to fix.

11in 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 Mercedes-Benz Citan follows the pattern of the model years either side. Its main cause of failure was Brake light, about 15 in every 100 failed tests. In 2025, 61.7% of 3,388 first MOTs on the 2018 Mercedes-Benz Citan 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 1,298 failed first-attempt MOT tests (test year 2025), Brake light (rear) appears more often than on similar cars (15.0% of those tests; 194 observed failures; about 5.4× 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 Mercedes-Benz Citan at the first attempt were Brake light (15.0%), Individual sidelight or tail light (front) (14.8%) and Drive shaft joints and boots (front) (14.1%), 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 light (rear) (15.0% of those tests; 194 observed failures; about 5.4× more often than similar cars). These are statistical signals, not a diagnosis of any individual car.
Brake light (rear) shows up more often than on similar cars (15.0% of those tests; 194 observed failures; about 5.4× 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 checkpoint, not a manufacturer service bulletin.
Common MOT problem areas for the 2018 Mercedes-Benz Citan include Brake light (rear), Drive shaft joints and boots (front), Individual sidelight or tail light (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 2018 Mercedes-Benz Citan (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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