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Common problems by part

Mercedes-Benz SLC lights and electrics problems

DVSA MOT tests 2022–2025 · 8,273 MOT tests · Updated

At 6 years, 1.7 in 100 MOT tests of the Mercedes-Benz SLC failed on lights and electrics, against 4.7 for all class 4 vehicles the same age (all test years; 8,273 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 (0.3–0.4×) (all test years), 142 MOT tests with a fail
  • By age: seen at 7 ages from 3 to 9 years, 35,306 MOT tests
  • Most common fail: Headlamp aim: too low, 0.6 per 100 MOT tests

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

What the MOT tests show

What we know

1.7 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 SLC 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 SLC lights and electrics fails by age

Mercedes-Benz SLC lights and electrics fails per 100 MOT tests by ageSolid line: the Mercedes-Benz SLC. Dashed line: all cars the same age. The table below lists every value.05103 years: 1.6 per 100 (all cars 2.9), 1,838 MOT tests34 years: 1.4 per 100 (all cars 3.1), 3,349 MOT tests45 years: 1.5 per 100 (all cars 3.7), 6,599 MOT tests56 years: 1.7 per 100 (all cars 4.7), 8,273 MOT tests67 years: 2.0 per 100 (all cars 5.8), 7,266 MOT tests78 years: 2.1 per 100 (all cars 7.3), 5,715 MOT tests89 years: 2.3 per 100 (all cars 9.2), 2,266 MOT tests9
Fails per 100 MOT tests by age, all first-use years pooled. Mercedes-Benz SLC All class 4 vehicles the same age
AgeMOT testsFails per 100All class 4 vehicles the same age
31,8381.62.9
43,3491.43.1
56,5991.53.7
68,2731.74.7
77,2662.05.8
85,7152.17.3
92,2662.39.2

All first-use years of the Mercedes-Benz SLC pooled at each age, against all class 4 vehicles at that age over all 2022–2025 test years.

What fails in the lights and electrics at 6 years

Fails

  • Headlamp aim: too low: 0.6 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
  • Headlight aimed too high: 0.4 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 SLC? 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 SLC, not the average

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

Other Mercedes-Benz SLC problems

Lights and electrics on rival models

Questions people ask

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

0.3 to 0.4 times the lights and electrics fail rate of all class 4 vehicles the same age at 6 years (all test years), from 8,273 MOT tests. The interval is clear of 0.8 in the same direction at 3 of the 7 ages seen (ages up to 18 with at least 100 MOT tests with a fail).

How common are Mercedes-Benz SLC lights and electrics problems?

1.7 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; 8,273 MOT tests).

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

0.6 in 100 MOT tests at 6 years: Headlamp aim: too low (46 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, 35,306 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