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Mercedes-Benz S-Class lights and electrics problems

DVSA MOT tests 2022–2025 · 10,214 MOT tests · Updated

At 6 years, 1.0 in 100 MOT tests of the Mercedes-Benz S-Class failed on lights and electrics, against 4.7 for all class 4 vehicles the same age (all test years; 10,214 MOT tests) [1].

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  • Against all class 4 vehicles the same age: fails less often than all class 4 vehicles the same age (0.2–0.3×) (all test years), 107 MOT tests with a fail
  • By age: seen at 21 ages from 3 to 23 years, 107,268 MOT tests
  • Most common fail: Headlamp aim: too low, 0.3 per 100 MOT tests

Figures are for the model as a whole, not for one car.

What the MOT tests show

What we know

1.0 fails per 100 MOT tests at 6 years, against 4.7 for all class 4 vehicles tested at 6 (all test years). The Mercedes-Benz S-Class fails less often here.

Why it matters

A lights and electrics fail stops the car passing until it is fixed; the most common one is rated major by DVSA.

What to check

Walk round with the lights, indicators, brake lights and hazards on (ask someone to press the pedal) and check every dashboard warning light goes out after starting.

Mercedes-Benz S-Class lights and electrics fails by age

Mercedes-Benz S-Class lights and electrics fails per 100 MOT tests by ageSolid line: the Mercedes-Benz S-Class. Dashed line: all cars the same age. The table below lists every value.010203 years: 0.9 per 100 (all cars 2.9), 4,741 MOT tests34 years: 0.7 per 100 (all cars 3.1), 6,757 MOT tests5 years: 0.8 per 100 (all cars 3.7), 8,358 MOT tests56 years: 1.0 per 100 (all cars 4.7), 10,214 MOT tests7 years: 1.1 per 100 (all cars 5.8), 9,775 MOT tests78 years: 1.4 per 100 (all cars 7.3), 9,073 MOT tests9 years: 1.9 per 100 (all cars 9.2), 7,642 MOT tests910 years: 2.1 per 100 (all cars 11.2), 6,202 MOT tests11 years: 2.5 per 100 (all cars 13.3), 4,903 MOT tests1112 years: 3.4 per 100 (all cars 15.4), 4,192 MOT tests13 years: 3.8 per 100 (all cars 17.0), 4,061 MOT tests1314 years: 5.8 per 100 (all cars 18.3), 3,924 MOT tests15 years: 6.7 per 100 (all cars 19.5), 4,369 MOT tests1516 years: 7.5 per 100 (all cars 20.4), 4,557 MOT tests17 years: 8.1 per 100 (all cars 21.0), 4,001 MOT tests1718 years: 8.0 per 100 (all cars 21.4), 3,665 MOT tests19 years: 10.9 per 100 (all cars 21.5), 3,100 MOT tests1920 years: 11.9 per 100 (all cars 21.2), 2,470 MOT tests21 years: 10.8 per 100 (all cars 20.6), 2,170 MOT tests2122 years: 11.9 per 100 (all cars 19.7), 1,776 MOT tests23 years: 13.9 per 100 (all cars 18.6), 1,318 MOT tests23
Fails per 100 MOT tests by age, all first-use years pooled. Mercedes-Benz S-Class All class 4 vehicles the same age Shaded: over 18 years, survivors only.
AgeMOT testsFails per 100All class 4 vehicles the same age
34,7410.92.9
46,7570.73.1
58,3580.83.7
610,2141.04.7
79,7751.15.8
89,0731.47.3
97,6421.99.2
106,2022.111.2
114,9032.513.3
124,1923.415.4
134,0613.817.0
143,9245.818.3
154,3696.719.5
164,5577.520.4
174,0018.121.0
183,6658.021.4
19*3,10010.921.5
20*2,47011.921.2
21*2,17010.820.6
22*1,77611.919.7
23*1,31813.918.6

All first-use years of the Mercedes-Benz S-Class pooled at each age, against all class 4 vehicles at that age over all 2022–2025 test years. * Only survivors are still tested at this age.

What fails in the lights and electrics at 6 years

Fails

  • Headlamp aim: too low: 0.3 fails per 100 MOT tests, all class 4 vehicles 0.8. Adjust headlamp aim: estimated £16–£39 (0.2–0.5 h at £78/h (ONS local-garage repair quotes, 1,058 quotes from 65 garages, Sep 2025 to Aug 2026) + parts) Headlamp aim too low MOT fail
  • Rear fog lamp: not working: 0.2 fails per 100 MOT tests, all class 4 vehicles 0.2. Replace exterior lamp bulb (position, stop, indicator, fog, reverse, number plate): estimated £11–£47 (0.1–0.5 h at £78/h (ONS local-garage repair quotes, 1,058 quotes from 65 garages, Sep 2025 to Aug 2026) + parts £3–£8) Rear fog lamp not working MOT fail
  • Headlight aimed too high: 0.2 fails per 100 MOT tests, all class 4 vehicles 0.6. Adjust headlamp aim: estimated £16–£39 (0.2–0.5 h at £78/h (ONS local-garage repair quotes, 1,058 quotes from 65 garages, Sep 2025 to Aug 2026) + parts) Headlamp aim too high MOT fail

Adjust headlamp aim cost

Repair figures are estimates, not quotes: how we estimate repair costs.

Buying a Mercedes-Benz S-Class? Check that exact car before the viewing.

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  • Model risks for this year and fuel
  • What similar cars did at their next MOT
  • Repairs ahead
  • Viewing checklist

See a sample report

How to check on a test drive

Walk round with the lights, indicators, brake lights and hazards on (ask someone to press the pedal) and check every dashboard warning light goes out after starting.

Check one Mercedes-Benz S-Class, not the average

The figures here describe Mercedes-Benz S-Class cars as a group. These free tools answer for one car. Each line says what the tool reads.

Other Mercedes-Benz S-Class problems

Lights and electrics on rival models

Questions people ask

Does the Mercedes-Benz S-Class have more lights and electrics problems than other cars?

0.2 to 0.3 times the lights and electrics fail rate of all class 4 vehicles the same age at 6 years (all test years), from 10,214 MOT tests. The interval is clear of 0.8 in the same direction at 13 of the 21 ages seen (ages up to 18 with at least 100 MOT tests with a fail).

How common are Mercedes-Benz S-Class lights and electrics problems?

1.0 in 100 MOT tests at 6 years failed on lights and electrics, against 4.7 for all class 4 vehicles the same age (all test years; 10,214 MOT tests).

What is the most common Mercedes-Benz S-Class lights and electrics fail?

0.3 in 100 MOT tests at 6 years: Headlamp aim: too low (27 MOT tests with it).

Sources

  1. Driver and Vehicle Standards Agency, Anonymised MOT tests and results, 2022 to 2025. DVSA MOT data, Open Government Licence v3.0, 107,268 MOT tests. Accessed 7 Oct 2026.
  2. Office for National Statistics, Consumer price inflation, local price quotes (car repair items). ONS price quotes, series 610236. Accessed 7 Oct 2026.

Parts: against all class 4 vehicles at the same age, all 2022–2025 test years pooled, not adjusted for mileage. Breakdowns and non-MOT faults are not in this data. How we compare