Mazda MX-5 2004: reliability & common MOT faults

In 2025, 64 in every 100 first MOTs on a 2004 Mazda MX-5 were passes. Most common reason for a fail: Petrol emissions (with catalyst).

Summary

The 2004 Mazda MX-5 follows the pattern of the model years either side.

At a glance

How 2,580 first tests went in 2025.

Passed first time
64 in every 100
Did not pass first time
36 in every 100925 failed first-attempt tests
The typical car
21 yearsabout 77,642 miles
First tests counted
2,580

What failed most often

  1. Petrol emissions (with catalyst)16 in every 100 failed tests
  2. Individual sidelight or tail light (front)12 in every 100 failed tests
  3. Handbrake efficiency below minimum (roller test)10 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 2004 Mazda MX-5 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.

Seat belts and restraints

One fault: seat belt mounting area (rear), 11 times as often as on similar cars.

Figures below are measured across the 924 of 925 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.

Seat belt mounting area (rear)

Failed on 77 first tests11 times as often as similar carsLikely evidence

What it means

A seat belt anchorage likely to become detached in the event of a collision is graded Dangerous. The load bearing structure near an anchorage, called a prescribed area, is Major when its strength or continuity is significantly reduced or it is inadequately repaired. Anchorage points are inspected for all seat belts fitted, except a belt with no corresponding seat.

Also noted as an advisory

Testers also noted it as an advisory, worn but not yet failing, on 29 first tests, 13 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.

Suspension

One fault: suspension mounting area (front), 6.3 times as often as on similar cars.

Suspension mounting area (front)

Failed on 83 first tests6.3 times as often as similar carsLikely evidence

What it means

The load bearing structure within a set distance of a sub-frame, spring or suspension component mounting is a prescribed area. Major applies when its strength or continuity is significantly reduced or it is inadequately repaired. Dangerous applies when it is so weakened that control of the vehicle is likely to be adversely affected.

Also noted as an advisory

Testers also noted it as an advisory, worn but not yet failing, on 32 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.

Body and structure

Four faults. The strongest is the vehicle structure condition (rear): 5.8 times as often as on similar cars.

Vehicle structure condition (rear)

Failed on 54 first tests5.8 times as often as similar carsLikely evidence

What it means

Structure that is fractured, deformed, corroded, modified or inadequately repaired is failed on rigidity only if the overall structural rigidity of the vehicle is significantly reduced. Structure that is likely to affect steering or braking adversely is graded Dangerous. Prescribed areas are not covered here, as they are checked under other sections, including brakes and steering.

Also noted as an advisory

Testers also noted it as an advisory, worn but not yet failing, on 40 first tests, 3.8 times as often as on similar cars.

Chassis condition (front)

Failed on 49 first tests5.6 times as often as similar carsLikely evidence

What it means

A main load-bearing structural member that is fractured, deformed, modified or inadequately repaired is Major when structural rigidity is significantly reduced, and Dangerous where steering or braking is likely to be adversely affected. Corrosion of the body, cab or chassis at a mounting point is Dangerous where overall security or stability is impaired.

Also noted as an advisory

Testers also noted it as an advisory, worn but not yet failing, on 33 first tests, 5.2 times as often as on similar cars.

Vehicle structure condition (front)

Failed on 26 first tests3.7 times as often as similar carsPossible evidence

What it means

Structure that is fractured, deformed, corroded, modified or inadequately repaired is failed on rigidity only if the overall structural rigidity of the vehicle is significantly reduced. Structure that is likely to affect steering or braking adversely is graded Dangerous. Prescribed areas are not covered here, as they are checked under other sections, including brakes and steering.

Also noted as an advisory

Testers also noted it as an advisory, worn but not yet failing, on 31 first tests, 5.1 times as often as on similar cars.

Chassis condition (rear)

Failed on 36 first tests2.9 times as often as similar carsPossible evidence

What it means

A main load-bearing structural member that is fractured, deformed, modified or inadequately repaired is Major when structural rigidity is significantly reduced, and Dangerous where steering or braking is likely to be adversely affected. Corrosion of the body, cab or chassis at a mounting point is Dangerous where overall security or stability is impaired.

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

Brakes

Two faults and one wear pattern. The strongest is the handbrake performance (roller test, rear): 3.7 times as often as on similar cars.

Handbrake performance (roller test, rear)

Failed on 34 first tests3.7 times as often as similar carsLikely evidence

What it means

A parking brake that is inoperative on one side is Major. When tested on the road, the failure is the vehicle deviating excessively from a straight line. Vehicles whose parking brake was already tested as the secondary brake are not tested again for this.

Brake pads (rear)

Failed on 39 first tests2.6 times as often as similar carsWear pattern

What it means

A pad worn down to its wear indicator, or contaminated with oil or grease, is Major. A pad worn below the set thickness limit, missing or incorrectly mounted is Dangerous. The manual treats an illuminated brake wear indicator as no reason for failure, although DVSA also lists an illuminated indicator as a Major row.

Also noted as an advisory

Testers also noted it as an advisory, worn but not yet failing, on 68 first tests, 3.0 times as often as on similar cars.

Brake performance (roller test, front)

Failed on 50 first tests2.5 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 55 first tests, 2.6 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.

Noise, emissions and leaks

One fault: petrol emissions (with catalyst), 2.7 times as often as on similar cars.

Petrol emissions (with catalyst)

Failed on 149 first tests2.7 times as often as similar carsPossible evidence

What it means

Emissions levels over the manufacturer's specified limits are Major, as are levels over default limits, which apply when no exact match is found for the vehicle. Dense blue or clearly visible black smoke at idle, held for a set period, is Major, except for certain older vehicles and two stroke engines where smoke is unavoidable. An induction or exhaust leak that could affect emissions levels is Major too.

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.

Anti-roll bar linkage ball joints (rear)

Noted on 20 first tests4.7 times as often as similar carsElevated evidence

Suspension arm (rear)

Noted on 95 first tests4.4 times as often as similar carsElevated evidence

Suspension arm (front)

Noted on 76 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
64in every 100
Passed on the first test.
Fixed at the station
5in every 100
Failed, then fixed at the test station the same day.
Failed
31in every 100
Did not pass, and were not fixed at the test station.

First-attempt pass 64.1% of 2,580 first tests (2025): only cars that passed first time count. Official-style pass 68.9%: cars fixed at the test station also count as a pass. The 5 fixed and the 31 not fixed make the 36 in every 100 that did not pass first time.

Same model, other years

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

4060801001990199520002004201020152020Older carsNewer cars
40608010019902000200420102020Older carsNewer cars

Newer cars are younger, so look for a jump rather than the climb.

YearPassed first timeFirst tests
199068 in every 100706
199164 in every 100756
199262 in every 100556
199367 in every 100523
199467 in every 100465
199568 in every 100721
199666 in every 1001,076
199767 in every 1001,589
199868 in every 1002,159
199965 in every 1002,255
200062 in every 1002,217
200167 in every 1001,631
200265 in every 1002,616
200362 in every 1003,309
2004 This car64 in every 1002,580
200566 in every 1002,775
200667 in every 1005,552
200769 in every 1006,988
200868 in every 1004,996
200971 in every 1003,926
201073 in every 1004,428
201176 in every 1003,235
201279 in every 1002,987
201379 in every 1002,983
201481 in every 1002,754
201585 in every 1002,891
201686 in every 1003,934
201789 in every 1004,422
201889 in every 1004,111
201992 in every 1003,880
202092 in every 1001,038
202195 in every 1001,426
202294 in every 1001,300

If you are buying one

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

Mileage matters most on a 2004 Mazda MX-5.

Of 2004 Mazda MX-5 vehicles with under 51,000 miles, 77 in every 100 passed their 2025 MOT first time. With 103,000 miles or more, 60 in every 100 did.

Under 51,000511 tests
77
51,000–69,000504 tests
66
69,000–84,000 Typical car535 tests
59
84,000–103,000513 tests
59
103,000 and over516 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 51,00069,000–84,000103,000 and over
Petrol emissions (with catalyst)1.87.98.3
Individual sidelight or tail light (front)0.67.75.8
Handbrake efficiency below minimum (roller test)2.04.94.3
Suspension mounting area (front)1.45.62.7
Seat belt mounting area (rear)1.63.95.4

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


When a car fails

25in every 100

of failed cars had one item to fix.

51in every 100

of failed cars had three or more items to fix.

8in 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 2004 Mazda MX-5 follows the pattern of the model years either side. Its main cause of failure was Petrol emissions (with catalyst), about 16 in every 100 failed tests. In 2025, 64.1% of 2,580 first MOTs on the 2004 Mazda MX-5 passed first time (PRS: items fixed at the station the same day, counted as a fail). The official-style rate including PRS is 68.9%. Among 925 failed first-attempt MOT tests (test year 2025), Seat belt mounting area (rear) appears more often than on similar cars (8.3% of those tests; 77 observed failures; about 11× 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 2004 Mazda MX-5 at the first attempt were Petrol emissions (with catalyst) (16.1%), Individual sidelight or tail light (front) (12.4%) and Handbrake efficiency below minimum (roller test) (10.1%), 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: Seat belt mounting area (rear) (8.3% of those tests; 77 observed failures; about 11× more often than similar cars). These are statistical signals, not a diagnosis of any individual car.
Seat belt mounting area (rear) shows up more often than on similar cars (8.3% of those tests; 77 observed failures; about 11× 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 2004 Mazda MX-5 include Seat belt mounting area (rear), Suspension mounting area (front), Vehicle structure 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 2004 Mazda MX-5 (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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