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Mercedes Benz 420 MOT Check

MOT pass rates, common failures, and reliability data for the Mercedes Benz 420. Check any 420 by registration number below.

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82.0%

Avg Pass Rate

-8.2%

vs Mercedes Benz Avg

6

Year Ranges

Good

Reliability

Mercedes Benz 420 — MOT Reliability Overview

The Mercedes Benz 420 has an average MOT pass rate of 82.0%, which is 8.2 percentage points below the Mercedes Benz brand average of 90.2%. This is a strong result, indicating that the 420 is well-engineered and tends to age well mechanically. Owners can expect fewer surprises at MOT time.

The most common reasons a Mercedes Benz 420 fails its MOT are a suspension joint dust cover missing or no longer prevents the ingress of dirt etc, wiper blade missing or obviously not clearing the windscreen, the aim of a headlamp is not within limits laid down in the requirements. If you are preparing your 420 for its MOT, checking these areas first could save you a retest fee. Our detailed fault analysis includes estimated repair costs for each failure type.

Before buying a used Mercedes Benz 420, we recommend checking the full MOT history, write-off status, outstanding finance, and stolen vehicle status. These checks can be done for free using the registration number.

MOT Pass Rate by Year

How the Mercedes Benz 420 performs at MOT across different model years.

1991

Based on 55 vehicles

78.2%Good
Mercedes Benz average: 90.2%
Dangerous Defects

0.0%

Retest Rate

22.2%

1990

Based on 134 vehicles

73.9%Average
Mercedes Benz average: 90.2%
Dangerous Defects

2.8%

Retest Rate

16.8%

1989

Based on 443 vehicles

87.6%Excellent
Mercedes Benz average: 90.2%
Dangerous Defects

0.6%

Retest Rate

7.6%

1988

Based on 589 vehicles

85.2%Excellent
Mercedes Benz average: 90.2%
Dangerous Defects

1.4%

Retest Rate

10.2%

1987

Based on 509 vehicles

82.5%Good
Mercedes Benz average: 90.2%
Dangerous Defects

1.1%

Retest Rate

14.2%

1986

Based on 338 vehicles

84.3%Good
Mercedes Benz average: 90.2%
Dangerous Defects

2.0%

Retest Rate

12.1%

Top MOT Failures — Mercedes Benz 420

The most common reasons a Mercedes Benz 420 fails its MOT, aggregated across all year ranges.

1

A suspension joint dust cover missing or no longer prevents the ingress of dirt etc

3.6%
2

Wiper blade missing or obviously not clearing the windscreen

3.3%
3

The aim of a headlamp is not within limits laid down in the requirements

2.6%
4

A tyre seriously damaged

2.4%
5

Number plate does not conform to the specified requirements

2.0%
Mercedes Benz 420 Common Faults & Repair Costs

Where Failures Occur

The areas of the vehicle most commonly flagged during MOT inspections.

Nearside

7.3%

Front Nearside Outer

3.6%

Rear Nearside

3.6%

Other Mercedes Benz Models

Compare MOT reliability across Mercedes Benz models.

Mercedes Benz E 300

94.2% pass rate

Mercedes Benz E

83.5% pass rate

Mercedes Benz Amg Gla 45 S 4matic+ Auto

92.7% pass rate

Mercedes Benz V

85.8% pass rate

Mercedes Benz Vito 112

87.8% pass rate

Mercedes Benz Sl 500

100.0% pass rate

Useful MOT Guides

Common MOT Failures

The most common reasons UK vehicles fail their MOT — and how to prepare.

MOT Checklist

Pre-MOT checklist to improve your chances of passing first time.

Advisory vs Failure

Understanding the difference between MOT advisories and failures.

See detailed fault analysis for Mercedes Benz 420

Mercedes Benz 420 — Frequently Asked Questions

Common questions about the Mercedes Benz 420 MOT and reliability.

What is the MOT pass rate for the Mercedes Benz 420?
The average MOT pass rate for the Mercedes Benz 420 is 82.0% compared to the Mercedes Benz average of 90.2%. Pass rates vary by year — check the year-by-year breakdown on this page for details.
What are the most common MOT failures on a Mercedes Benz 420?
The most common MOT failures on the Mercedes Benz 420 are: A suspension joint dust cover missing or no longer prevents the ingress of dirt etc (3.6%), Wiper blade missing or obviously not clearing the windscreen (3.3%), The aim of a headlamp is not within limits laid down in the requirements (2.6%). These are the components most likely to cause an MOT failure.
Is the Mercedes Benz 420 reliable?
With an average MOT pass rate of 82.0%, the Mercedes Benz 420 is rated as "Good" for reliability. This is a strong result suggesting good build quality and fewer common defects.
How do I check the MOT history of a Mercedes Benz 420?
Enter the vehicle's registration number in the search box at the top of this page. You will instantly see the complete MOT history including every test result, mileage readings, advisories, and dangerous defects — completely free.
What mileage should I expect on a Mercedes Benz 420?
Mileage data for the Mercedes Benz 420 is available in the detailed breakdown on this page.

Check Your Mercedes Benz 420's MOT History

Enter the registration number for the full MOT history — free and instant.

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