2021 Mercedes-Benz Amg A 45 S 4Matic+ — MOT failures & pass rate
Across 635 MOT tests, the 2021 Mercedes-Benz Amg A 45 S 4Matic+ recorded a 90.5% pass rate. All cars of a similar age fail at 8.6%, so the 2021 Amg A 45 S 4Matic+ sits squarely on the average. Failures cluster in tyres, lighting & signalling and emissions & environmental.
What the MOT record shows
Tyres dominates the failure mix at 6.6% of all tests — 4.9 points clear of lighting & signalling, so it is the first thing to check.
At component level the recurring items are headlamp aim, catalyst emissions and tread depth — headlamp aim alone was recorded 14 times.
Advisories point at the next bill rather than this one: tyres was flagged on 12.8% of tests without failing them.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 6.6% | 42 |
| 2 | Lighting & signalling | 1.7% | 11 |
| 3 | Emissions & environmental | 1.6% | 10 |
| 4 | Visibility | 0.8% | 5 |
| 5 | Other defects | 0.8% | 5 |
| 6 | Brakes | 0.5% | 3 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Headlamp aim | 14 |
| 2 | Catalyst emissions | 13 |
| 3 | Tread depth | 10 |
| 4 | Registration plates | 9 |
| 5 | Washers | 3 |
| 6 | Rear reflectors | 2 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Tyres | 12.8% | 81 |
| 2 | Visibility | 4.3% | 27 |
| 3 | Brakes | 3.8% | 24 |
| 4 | Other defects | 3.8% | 24 |
| 5 | Suspension | 0.9% | 6 |
| 6 | Road wheels | 0.5% | 3 |
Failure rate by mileage
Higher-mileage cars tend to fail more — often the most useful guide to real condition.
| Mileage band | Tests | Fail rate |
|---|---|---|
| 0-30k | 465 | 8.4% |
| 30-60k | 160 | 12.5% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2024 | 303 | 8.9% |
| 2025 | 313 | 9.9% |
What to check before buying a 2021 Amg A 45 S 4Matic+
On a 2021 Amg A 45 S 4Matic+, tyres is what the MOT record says goes wrong most — it appeared in 6.6% of tests. Check these areas before you commit.
- Tyres (6.6% of tests): Usually a quick, known-cost fix, but check tread, age and uneven wear (which can hint at alignment or suspension issues). Typical repair: £50–£120 per tyre.
- Lighting & signalling (1.7% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Emissions & environmental (1.6% of tests): More common on older diesels (DPF/EGR) — can be expensive; check for warning lights and smoke. Typical repair: £100–£600.
Repair costs are rough UK ballpark ranges to set expectations, not quotes — actual prices vary widely by car, parts and garage.
Frequently asked questions
How many 2021 Mercedes-Benz Amg A 45 S 4Matic+s pass their MOT?
90.5% of the 635 2021 Mercedes-Benz Amg A 45 S 4Matic+ MOT tests in this dataset passed — a 9.4% fail rate.
What is the most common MOT failure on a 2021 Mercedes-Benz Amg A 45 S 4Matic+?
Tyres, recorded in 6.6% of tests, followed by lighting & signalling (1.7%).
Does the 2021 Amg A 45 S 4Matic+ get worse with mileage?
Its MOT fail rate rises from 8.4% in the 0-30k band to 12.5% in the 30-60k band.
Methodology & source. Based on 635 MOT tests. Dataset: DVSA MOT testing data (2021,2022,2023,2024,2025). Data last updated 2026-07-27. Figures reflect MOT-testable defects only — read the methodology for how these are calculated and what they don't measure.