1990 Mercedes-Benz S-Class — MOT failures & pass rate
Across 271 MOT tests, the 1990 Mercedes-Benz S-Class recorded an 83.0% pass rate. Executive cars of a similar age fail 18.4% of the time, so this is 1.5pp better than the group it competes with. Failures cluster in lighting & signalling, suspension and emissions & environmental.
What the MOT record shows
No single area dominates — lighting & signalling (10.7%) and suspension (8.1%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are headlamp aim, component mounting prescribed areas and ball joint dust cover — headlamp aim alone was recorded 12 times.
Mileage matters less than usual here: the 1990 S-Class fails 20.8% of the time in the 60-90k band and 19.4% at 150k+, a spread of only 1.5 points.
Advisories point at the next bill rather than this one: suspension was flagged on 26.9% of tests without failing them.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 10.7% | 29 |
| 2 | Suspension | 8.1% | 22 |
| 3 | Emissions & environmental | 4.8% | 13 |
| 4 | Body, structure & corrosion | 4.1% | 11 |
| 5 | Visibility | 3.7% | 10 |
| 6 | Brakes | 3.7% | 10 |
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 | 12 |
| 2 | Component mounting prescribed areas | 11 |
| 3 | Ball joint dust cover | 10 |
| 4 | Non catalyst emissions | 10 |
| 5 | Headlamp | 8 |
| 6 | Wipers | 7 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Suspension | 26.9% | 73 |
| 2 | Brakes | 25.5% | 69 |
| 3 | Emissions & environmental | 20.3% | 55 |
| 4 | Tyres | 14.0% | 38 |
| 5 | Steering | 12.2% | 33 |
| 6 | Body, structure & corrosion | 10.0% | 27 |
Failure rate by mileage
Higher-mileage cars tend to fail more — often the most useful guide to real condition.
| Mileage band | Tests | Fail rate |
|---|---|---|
| 60-90k | 48 | 20.8% |
| 90-120k | 53 | 9.4% |
| 120-150k | 55 | 14.5% |
| 150k+ | 93 | 19.4% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 68 | 19.1% |
| 2022 | 58 | 17.2% |
| 2023 | 55 | 16.4% |
| 2024 | 41 | 12.2% |
| 2025 | 49 | 18.4% |
What to check before buying a 1990 S-Class
On a 1990 S-Class, lighting & signalling is what the MOT record says goes wrong most — it appeared in 10.7% of tests. Check these areas before you commit.
- Lighting & signalling (10.7% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Suspension (8.1% of tests): Worn drop links, bushes, springs or shocks — listen for knocks over bumps and check for uneven tyre wear. Typical repair: £150–£450 per corner.
- Emissions & environmental (4.8% 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 1990 Mercedes-Benz S-Classs pass their MOT?
83.0% of the 271 1990 Mercedes-Benz S-Class MOT tests in this dataset passed — a 17.0% fail rate.
What is the most common MOT failure on a 1990 Mercedes-Benz S-Class?
Lighting & signalling, recorded in 10.7% of tests, followed by suspension (8.1%).
Does the 1990 S-Class get worse with mileage?
Its MOT fail rate rises from 20.8% in the 60-90k band to 19.4% in the 150k+ band.
Methodology & source. Based on 271 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.