Mercedes-Benz S400 MOT reliability

Mercedes-Benz S400s passed their MOT first time 79% of the time across 14 tests in 2025.

These figures come from only 14 MOT tests. With so few cars, a single pass or fail changes the percentages a lot, so treat them as a rough guide rather than a true average.

First-time pass rate

79%

MOTs analysed

14

Still licensed (GB)

–

Body type

–

Pass rate by year of first registration

Older cars fail more often, so compare a car with others of the same age. Years with very few MOTs can show extreme pass rates, even 0% or 100%, so give more weight to years with more tests.

In detail:

First registered

2004 diesel

1 MOT

Passed first time 0%. Typical mileage 202,192 (most between 202,192 and 202,192).

2007: 100% → 2008: 100% → 2010: 100% → 2011: 100% → 2012: 100% → 2013: 100% → 2014: 100% → 2015: 100% → 2016: 100% → 2017: 100% → 2018: 100% → 2019: 100% → 2020: 100% → 2022: 100% → 2023: 100% → 2024: 50% → 2025: 0%

Most common failures

Registration plate lamp(s): inoperative in the case of a single lamp or all lamps (100.0%)
Exhaust system: has a major leak of exhaust gases (100.0%)

Where 2004 S400s fail

Body, structure & corrosion

100.0%

Lights & electrics

100.0%

Looking at a particular car?

See its own MOT history, mileage and red flags, compared with these figures. Free.

Based on 2025 initial MOT tests in DVSA's anonymised MOT dataset (cars and light vans). Contains public sector information licensed under the Open Government Licence v3.0. Model details: Vehicle data by VehiclesDB.