1989 Mercedes 420 Sec MOT Pass Rate
Pass rate for 420 Sec models manufactured in 1989, based on 347 real MOT test results.
Data from official DVSA MOT testing records
This page shows all 420 Sec cars tested in 1989. Want to see how cars built in 1989 hold up over time?
View 1989 Mercedes 420 Sec vintage page → (66.7% current pass rate)1989 Mercedes 420 Sec MOT Analysis
The 1989 Mercedes 420 Sec has an MOT pass rate of 70.0% based on 347 tests — slightly above the UK average for UK vehicles. Cars of this vintage present for MOT with an average of 113,126 miles on the odometer. With a 30.0% failure rate, the 1989 420 Sec is rated as "Good" for MOT reliability.
The leading cause of MOT failure for the 1989 Mercedes 420 Sec is Visibility, responsible for 0.9% of failures. Visibility failures relate to the windscreen, wipers, washers, mirrors, and view-obstructing damage. Cracks in the windscreen swept area, ineffective wipers, or empty washer bottles are common causes. Typical repair costs range from £10–300. Brakes is the second most common issue at 0.6%. Noise, emissions and leaks follows at 0.3%.
Top failures specific to 1989 models only. The overall 420 Sec page may show different rankings.
What Fails Most
What Fails on This Car?
Click a category to see specific failure items.
View as table
| Rank | Failure Category | Rate (%) | Count |
|---|---|---|---|
| 1 | Visibility | 0.9% | 3 |
| 2 | Brakes | 0.6% | 2 |
| 3 | Noise, Emissions And Leaks | 0.3% | 1 |
| 4 | Suspension | 0.3% | 1 |
Failures per 10,000 Miles
avg. 113,126 miFor every 10,000 miles driven, this shows what percentage of MOT tests fail for each category. This accounts for how far cars are actually driven, not just raw pass/fail counts.
View as table
| Category | Rate / 10K mi | Raw % | Count |
|---|---|---|---|
| Visibility | 0.08 | 0.9% | 3 |
| Brakes | 0.05 | 0.6% | 2 |
| Noise, emissions and leaks | 0.03 | 0.3% | 1 |
| Suspension | 0.03 | 0.3% | 1 |
Mileage Statistics
Mileage-adjusted failure rate — accounts for how much this model year is typically driven.
About This Data
The 1989 Mercedes 420 Sec has an MOT pass rate of 70.0% based on 347 tests — slightly above the UK average for UK vehicles. Cars of this vintage present for MOT with an average of 113,126 miles on the odometer. With a 30.0% failure rate, the 1989 420 Sec is rated as "Good" for MOT reliability.
If you own or are considering buying a 1989 Mercedes 420 Sec, you can expect reliable MOT performance overall. Before your MOT, pay particular attention to visibility: Check the windscreen for chips and cracks — damage larger than 10mm in the driver's swept area or 40mm elsewhere will fail. Test washers and wipers. Ensure both door mirrors are intact and adjustable. With an average mileage of 113,126 miles, these vehicles are in the higher-mileage bracket where wear-related failures become more common.
Visibility — 0.9% of failures
Visibility issues account for 0.9% of MOT failures on 1989 Mercedes 420 Sec models. Visibility failures relate to the windscreen, wipers, washers, mirrors, and view-obstructing damage. Cracks in the windscreen swept area, ineffective wipers, or empty washer bottles are common causes. Typical repair costs: £10–300. Pre-MOT check: Check the windscreen for chips and cracks — damage larger than 10mm in the driver's swept area or 40mm elsewhere will fail. Test washers and wipers. Ensure both door mirrors are intact and adjustable.
Brakes — 0.6% of failures
Brakes issues account for 0.6% of MOT failures on 1989 Mercedes 420 Sec models. Brake-related failures include worn brake pads, corroded brake discs, leaking brake lines, and faulty brake servos. These are safety-critical components — any brake deficiency will result in an MOT fail. Typical repair costs: £150–400. Pre-MOT check: Listen for squealing or grinding noises. Check brake pedal feel — if it feels spongy or goes to the floor, have the system inspected immediately. Look at brake pad thickness through the wheel spokes (minimum 3mm).
Noise, emissions and leaks — 0.3% of failures
Noise, emissions and leaks issues account for 0.3% of MOT failures on 1989 Mercedes 420 Sec models. Emissions failures occur when exhaust gases exceed legal limits for carbon monoxide (CO), hydrocarbons (HC), or particulate matter (diesel). Common causes include faulty oxygen sensors, clogged catalytic converters, or DPF issues on diesel vehicles. Typical repair costs: £100–1,000+. Pre-MOT check: If the engine management light is on, get it diagnosed before the MOT. For diesel cars, ensure the DPF has completed a regeneration cycle. Regular servicing and using premium fuel before the test can help.
Based on DVSA anonymised MOT test data (2005–2024). Crown copyright, Open Government Licence v3.0.