Ford Sierra — MOT statistics 2024

The Ford Sierra failed 13.13% of 2,688 first MOT attempts in 2024 ("first-time", excluding retests). Adjusted for the age of the fleet, its initial-failure ratio is 38.0 (100 = expected for its age profile). This car fails its MOT about 62% less often than expected for its age. Small sample — treat with care.

Age-adjusted peer: Porsche Cayman (index 37.3) — the two published results are 0.7 index points apart.

Ford Sierra common problems: what actually fails the MOT

Lamps, reflectors and electrical equipment are well below the reference at 13.1 per 100 tests, against 29.6 per 100 tests across UK vehicles of the same ages.

higher bar = fails more oftenrate per 100 tests

family vs national — matched to UK vehicles of the same ages — top component groups, per 100 tests. Legend: This family · National avg. Combined labels: family / national average. A gap here reflects how these vehicles are driven, used and maintained as well as how they were built — an MOT defect is a test outcome, not a breakdown.

Named defects ranked by how much more often they appear than the national average — not by raw rate.

Ford Sierra MOT advisories: what gets flagged

Suspension is highest at 21.6 per 100 tests; Non-component advisories are lowest at 4.5 per 100 tests — the gap is 17.1 per 100 tests.

higher bar = flagged more oftenadvisory items per 100 initial tests

Advisories are wear the tester noted but didn't fail — what will need money soon.

If a car like this fails, does it fail again?

A failure rate does not say whether a failure is a one-off or the start of something. This follows the same vehicles into their next ordinary MOT a year later — retests after a repair are excluded, because they follow a failure by definition. 2019-2024.

A failed test raises next year's chance of failing again by 9.6 percentage points. The failure most likely to come back is steering — 30.2% of those vehicles fail again next year. Some of this is the vehicle and some is the owner: a car that was let go once tends to be let go again. One caveat: a car that fails may be sold or scrapped rather than tested again, so these figures describe the vehicles that came back.

Adjusted for how much these are actually driven

The headline index adjusts for the fleet's age. Wear, though, follows mileage: a three-year-old taxi and a three-year-old garage queen sit in the same age band. These two rows compare every car with vehicles of the same age, and then with vehicles of the same age and the same annual mileage, 2019-2024, on 15,153 tests. Both stand on the six-year corpus so they are measured on identical data — compare them with each other, not with the headline index above, which is measured on 2024 alone.

Split by how much each car is driven. This is a split by annual mileage, not by body type — the MOT record does not say whether a car is a conversion. Within each band the index compares with vehicles of the same age driven as much.

Mileage matters here: matching on how much these are driven moves the figure by 7.7 points — this fleet is driven less than the vehicles it is measured against, so the age-only view flatters it — but it does not change which side of normal the car sits on. One limit to keep in mind: mileage is partly a result of how often a car breaks down — one that spends weeks in the workshop covers fewer miles — so the mileage-matched figure can understate a real weakness. Tests with no usable odometer reading are left out of it.

How does the Ford Sierra perform as it gets older?

The Sierra at age 20 is well below the reference at 8.0%, against 41.0% for all vehicles of the same age.

higher = larger sharecompare shares in percentage points

Chart axes: car age, years · failure-rate scale 0–47%.

Takeaway: solid line: this family; dashed: all cars.

How dangerous are Ford Sierra MOT failures?

Major defects are well below the reference at 43.4 per 100 tests, against 52.8 per 100 tests nationally.

higher bar = fails more oftenrate per 100 tests

Chart values: Minor 10.6 · Major 43.4 · Dangerous 3.9.

Per 100 tests on this family. National average: Minor 14.2 · Major 52.8 · Dangerous 11.2 per 100.

Does the month of a Ford Sierra MOT matter?

Jan is highest at 22.7%; Jun is lowest at 14.2% — the gap is 8.4 percentage points.

higher = larger sharecompare shares in percentage points

Chart scale: 13%–33%.

bars: Ford Sierra · dashed: all class-4 cars

Takeaway: the spread between best and worst month is 8.4 percentage points — noticeable seasonality. Seasonality partly reflects registration-date clustering, not weather.

Before reading the shape: most of it is not about cars. Britain changes its registration plates twice a year, and 18.9% of these cars were first registered in March with another17.1% in September — 36% in two months against the 17% an even spread would give. An MOT falls due three years after first registration, so the buying calendar becomes the testing calendar. That shapes how many cars are tested each month — not how often they fail: the busiest months here are not the worst ones, so read the failure line on its own and the volume behind it separately.

Ford Sierra average mileage by age

At age 20+, the middle half of Sierras runs from 24,246 miles to 78,891 miles, against 53,949 miles as the median.

further right = more milesmedian is the typical car; band is p25–p75

Does high mileage mean more Ford Sierra MOT failures at the same age?

Within the same age group, split by odometer (2024 MOTs), so this separates wear from age: at ages 15+, 8.7% of those with under 40,000 miles failed first time versus 10.7% of those with 70,000–100,000 miles.No clear mileage gap inside this age group, among cars still being tested.

line: median · band: middle half of the fleet (p25–p75)

A typical 20+-year-old Sierra has ~53,949 miles on the clock. Much more — ask why; much less — check for gaps in the MOT history.

Where in Britain the Ford Sierra fails its MOT most

Bath area is highest at 27.4%; Crewe area is lowest at 7.3% — the gap is 20.1 percentage points.

higher = larger sharecompare shares in percentage points

Toughest areas	% failing	vs model overall
Bath (BA)	27.39%	+10.7 pp
Bristol (BS)	26.69%	+10.0 pp
Brighton (BN)	26.03%	+9.4 pp
Exeter (EX)	26.02%	+9.3 pp
Plymouth (PL)	24.9%	+8.2 pp

Easiest areas	% failing	vs model overall
Crewe (CW)	7.28%	-9.4 pp
Bolton (BL)	7.44%	-9.2 pp
Kilmarnock (KA)	7.64%	-9.0 pp
Romford (RM)	8.54%	-8.1 pp
Slough (SL)	8.97%	-7.7 pp

Every dot is a postcode area — size = how many were tested there, colour = share failing. These figures are not age-adjusted: coastal and rural areas often run older fleets and salted roads, so higher raw fail rates do not automatically mean a worse local stock of this model.

Map labels: Scotland · N. England · Wales · London · S. West. Colour scale: 11%–26% failing.

Ford Sierra faults that come together

Seatbelts & SRS + Suspension stand out at 9.58×, against 1.00× if the faults were independent.

above 1.0× = more than expectedbelow 1.0× = less

Defects in «Seat belts and supplementary restraint systems» and «Suspension» appear together 9.58× more often than chance (145 co-occurrences in the same test; 78 pairs compared).

Lift = how many times more often both groups appear on the same test than if independent. A pair is listed from 5 tests with both faults; the lift is shown from 20, and called above chance only when its 95% interval excludes 1 (see rough estimates).

Which Ford Sierra engine is best?

petrol 1.5–1.8 is highest at 146.9; petrol 1.8–2.0 is lowest at 78.4 — the gap is 68.5 points.

below 100 is betterabove 100 is worse100 = normal for this model at that age

Splitting this model by fuel alone hides the thing that actually differs. Within the same badge, the petrol 1.5–1.8 runs at 146.9 against this model's own age norm while the petrol 1.8–2.0 runs at 78.4 — a spread of 68.5 points between two cars that share a name.

Read this one with more care than the rest of the page. Age is held constant, but who buys which engine is not: the largest capacity in a range is often a performance or executive variant that is garaged, cherished and lightly driven, while the smallest is frequently a fleet or entry car worked hard from new. The gap below is real in the test records; how much of it is the engine and how much is the owner, this data cannot separate. Bands under 100 tests are not shown; bands under 5,000 tests are rough estimates.

Ford Sierra MOT repair costs

The MOT-failure repair budget per test runs from £58.00 to £110.20, against £54.85 for the test itself.

bigger number = costs morepounds per test, MOT-failing faults only

Multiply how often each component fails on this model by what that repair usually costs, and you get the amount an owner should expect to budget per test for MOT-failing faults only — roughly £58 to £110, on top of the test fee itself. It is a budgeting figure, not a quote: the spread between a set of pads and a set of discs is most of the range.

Prices are modal quotes from a hand-kept catalogue of published UK garage guides — we do not scrape the booking sites, their terms forbid it, so this list is short and updated by hand with a source and date against each line. Each line prices one typical repair in that group, not a full remedy, and only groups our catalogue actually covers are counted. The contrast worth noticing is the second card: the legal maximum for the test has been £54.85 since 2010, while the repairs it uncovers have followed inflation the whole time.

For scale from a different direction: Warrantywise, which sees used-car warranty claims rather than test failures, puts the average claim at £2,052 across the ten highest-claim models it ranks and £539 for Honda, the lowest-claim make in its index (Warrantywise index 2026, 1.6 million claims, cars aged 3–15). Those sit an order of magnitude above the figures in this table, and the gap is the point: a warranty claim is a gearbox or an engine, which almost never fails an MOT, while the faults that do fail one are corrosion, lamps and tyres, which no warranty pays for. The two numbers answer different questions and neither replaces the other.

Ford Sierra rust problems: where they corrode

Salt-belt exposure stands out at 54th percentile, against 50th percentile as the middle of published models.

higher = larger sharecompare shares in percentage points

This Ford Sierra has too few tests to judge for corrosion once age is held constant, and its owners live in areas that are about typical for the models we publish.

Corrosion is the one failure mode that is as much about geography as about the car. We keep the two apart on purpose: a model can look rusty simply because it is popular in Scotland, and a model can look clean simply because it is bought in Surrey. Blending them into a single score would hide which of the two is doing the work.

Exposure is this model's tests weighted by an area corrosion index built from frost days, salt load and distance to the coast — the composite validated at r = 0.42 against corrosion defects we actually record. It is published as a rank, not a raw score, because every mainstream model skews towards low-corrosion areas for the simple reason that most of Britain's cars are in the south. Susceptibility is standardised to the national age profile, so an old fleet does not get labelled a rusty model.

Does a Ford Sierra advisory become a failure?

Body, chassis, structure are highest at 13.3%; Tyres are lowest at 5.1% — the gap is 8.2 percentage points.

higher = more likelypercentage is the observed transition probability

chance the same component fails at the next MOT, given an advisory now

This is the question an advisory note actually raises, and it needs six years of test history to answer. We followed the same vehicles from one MOT to the next across 2019–2024 and measured how often a component that was merely advised came back as a genuine failure at the next test.

Read it as a budgeting horizon, not a prophecy: the most likely component above turns into a failure for about 13 in 100 cars, and the median gap is 12.2 months and roughly 917 miles. The rest were repaired, sold, scrapped, or simply held. Rows with fewer than 500 tracked advisories are not shown.

What will fail next on a Ford Sierra?

Lamps, reflectors and electrical equipment after a failure at age 20+ are highest at 12.8%; Body, chassis, structure after a passed at age 20+ are lowest at 2.7% — the gap is 10.1 percentage points.

higher = more likelypercentage is the observed transition probability

The same chains, cut differently: given a car's age and how its last test went, which component most often causes trouble at the following one.

The pattern that repeats across every family: a failure at one test roughly doubles the chance of a failure on the same component at the next one, and an advisory sits about half-way between a clean pass and a failure. Age bands in years; probabilities are per car, not per defect item.

Ford Sierra ownership: what six years of MOTs show

The ten-day re-test pass rate is highest at 67.3%; The later re-test pass rate is lowest at 13.4% — the gap is 54.0 percentage points.

higher = larger sharecompare shares in percentage points

Failing is usually a same-week event, not a disaster. Of 1,708 failures followed through to their re-test, 19.32% were repaired and passed the same day and 67.33% within ten days; the median gap is 3 days. 5,143 defect items were cleared in the process.

Per mile driven, not per year. Dividing failures by the miles that actually went onto the odometers between consecutive tests gives 1.139 failures per 10,000 miles, on a median of 315 miles a year across 4,033 chains. This is the number to compare between models — an annual rate quietly rewards cars that barely leave the drive.

Two populations hide inside one model. 61.31% of these cars strung together three or more tests with nothing recorded at all, while 15.56% carried the same advisory three times or more — the same fault, noted, ignored, noted again. When you buy used you are buying one of those two histories, and the MOT record shows which.

Odometer anomalies: 2.455% of 4,114 chains show a reading lower than the previous test, with a median drop of 22,178 miles. We call this an anomaly and not fraud on purpose — instrument swaps, imports, unit mix-ups and keying errors all land in the same bucket. Obvious typos (drops under 100 miles or over 90% of the reading) are already excluded.

Ford Sierra MOT: quick answers

Ford Sierra MOT Risk Index is well below the reference at 38.0, against 100 for a car with the same age profile.

below 100 is betterabove 100 is worse100 = normal for this model at that age

What is the Ford Sierra first-time MOT pass rate?

86.87% of first attempts passed in 2024 (2,688 tests). This is the first-time figure: retests after repair are excluded. Basis: first-time, excluding retests.

Why does this number differ from other sites?

Other sites often report a pass rate that includes retests or counts all attempts. Our 13.13% figure is the first-time initial failure rate, using 2,688 primary tests as the denominator (first-time, excluding retests). The age-adjusted MOT initial-failure ratio 38.0 is shown separately because raw rates compare fleet age as well as cars.

Compare the Ford Sierra with other cars

Lotus Elise is highest at 39.2; BMW M5 is lowest at 36.7 — the gap is 2.5 points.

below 100 is betterabove 100 is worse100 = normal for this model at that age

Same brand

All Ford MOT statisticsFord Escort MOT statsFord Puma MOT stats

Similar risk

Porsche Cayman (index 37.3)Lotus Elise (index 39.2)BMW M5 (index 36.7)

Same size class

how Maserati Levante compareshow Bentley Bentayga compareshow Mercedes-Benz GLS compares

By area

Ford Sierra MOT failure rate by postcode area

By failure group

Ford Sierra body, chassis and structure failuresFord Sierra brakes failuresFord Sierra vehicle identification failuresFord Sierra lamps, reflectors and electrics failuresFord Sierra noise, emissions and leaks failuresFord Sierra road wheels failuresFord Sierra seat belts and airbags failuresFord Sierra steering failuresFord Sierra suspension failuresFord Sierra tyres failuresFord Sierra visibility failures