1998 Mercedes-Benz S-Class — MOT failures & pass rate
1,076 MOT tests on the 1998 Mercedes-Benz S-Class are in this dataset, and 82.0% of them passed. Against executive cars of a similar age (22.7% fail rate), the 1998 S-Class comes out 4.7pp better. Failures cluster in lighting & signalling, brakes and suspension.
What the MOT record shows
No single area dominates — lighting & signalling (9.6%) and brakes (7.9%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are catalyst emissions, wipers and rigid brake pipes — catalyst emissions alone was recorded 62 times.
A 150k+ example is materially riskier than a 30-60k one: 22.8% versus 13.9%.
Advisories point at the next bill rather than this one: brakes was flagged on 29.7% of tests without failing them.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 9.6% | 103 |
| 2 | Brakes | 7.9% | 85 |
| 3 | Suspension | 7.2% | 77 |
| 4 | Visibility | 5.9% | 63 |
| 5 | Emissions & environmental | 4.1% | 44 |
| 6 | Body, structure & corrosion | 3.5% | 38 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Catalyst emissions | 62 |
| 2 | Wipers | 49 |
| 3 | Rigid brake pipes | 48 |
| 4 | Headlamp aim | 42 |
| 5 | Pins and bushes | 31 |
| 6 | Individual direction indicators | 30 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Brakes | 29.7% | 320 |
| 2 | Suspension | 27.9% | 300 |
| 3 | Emissions & environmental | 20.8% | 224 |
| 4 | Tyres | 16.6% | 179 |
| 5 | Other defects | 12.0% | 129 |
| 6 | Lighting & signalling | 11.6% | 125 |
Failure rate by mileage
Higher-mileage cars tend to fail more — often the most useful guide to real condition.
| Mileage band | Tests | Fail rate |
|---|---|---|
| 30-60k | 137 | 13.9% |
| 60-90k | 222 | 16.7% |
| 90-120k | 250 | 16.4% |
| 120-150k | 237 | 19.0% |
| 150k+ | 219 | 22.8% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 270 | 18.1% |
| 2022 | 246 | 19.5% |
| 2023 | 201 | 16.9% |
| 2024 | 186 | 18.3% |
| 2025 | 173 | 16.8% |
What to check before buying a 1998 S-Class
On a 1998 S-Class, lighting & signalling is what the MOT record says goes wrong most — it appeared in 9.6% of tests. Check these areas before you commit.
- Lighting & signalling (9.6% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Brakes (7.9% of tests): Pads/discs are routine wear; binding, imbalance or corroded pipes are more serious — test for pulling under braking. Typical repair: £100–£350 per axle.
- Suspension (7.2% 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.
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 1998 Mercedes-Benz S-Classs pass their MOT?
82.0% of the 1,076 1998 Mercedes-Benz S-Class MOT tests in this dataset passed — a 18.0% fail rate.
What is the most common MOT failure on a 1998 Mercedes-Benz S-Class?
Lighting & signalling, recorded in 9.6% of tests, followed by brakes (7.9%).
Does the 1998 S-Class get worse with mileage?
Its MOT fail rate rises from 13.9% in the 30-60k band to 22.8% in the 150k+ band.
Methodology & source. Based on 1,076 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.