Used car guide

2009 Mercedes-Benz SLK: common problems and what to check

What gets flagged at MOT on 2009 Mercedes-Benz SLKs, from 2,444 tests in 2025, plus known faults and what to look at before you buy one.

2,444MOT tests in 2025
69%pass first time (all 2009 cars: 58%)
4,300typical miles a year
2.1×the usual rate for rigid brake pipes

What stands out

Parts flagged at MOT more often on 2009 Mercedes-Benz SLKs than on all cars registered in 2009.

  • Rigid brake pipes2.1× usual
    Mercedes-Benz SLK
    15.6% All 2009 cars
    7.5%

    Failed outright at MOT: 2.5%, against 1.2% of all 2009 cars. The rest were advisories or minor defects.

    Rough price £100–£400 our estimate

    At the viewing: Ask to see underneath, or check the MOT advisories: corroded brake or fuel pipes get worse every year and fail the MOT when they do.

  • Individual direction indicators2× usual
    Mercedes-Benz SLK
    5.7% All 2009 cars
    2.9%

    Failed outright at MOT: 1.3%, against 1.2% of all 2009 cars. The rest were advisories or minor defects.

    Rough price £10–£80 our estimate

    At the viewing: Ask a friend to check every light while you work the switches: indicators, brake lights, fog lights and reversing lights.

  • Wheel bearings1.9× usual
    Mercedes-Benz SLK
    4.2% All 2009 cars
    2.2%

    Failed outright at MOT: 0.1%, against 0.8% of all 2009 cars. The rest were advisories or minor defects.

    Rough price £120–£300 (one bearing) ClickMechanic

    At the viewing: Listen for a hum or growl that changes as you steer at speed.

Better than most

Engine oil leaks: 2.5% here, against 10.4% of all 2009 cars. Number plate lights: 1.7% here, against 8.8% of all 2009 cars.

By area

The share of 2009 Mercedes-Benz SLK MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.

  • Suspension
    33% of testsRough price £120–£400

    At the viewing: Listen for knocks over speed bumps, and look behind each front wheel for a snapped coil spring.

  • Brakes
    29% of testsRough price £150–£350

    At the viewing: Look for a lip on the disc edges and feel for judder or pulling when braking firmly from about 40mph.

  • Tyres
    29% of testsRough price £70–£150

    At the viewing: Check the tread on all four tyres, including the inside edges, and look for cracks or bulges.

  • Lights and electrics
    22% of testsRough price £10–£80

    At the viewing: Ask a friend to check every light, including brake lights and indicators, while you operate them.

  • Wipers, windscreen and mirrors
    7% of testsRough price £15–£250

    At the viewing: Check for chips in the driver's view, and test the wipers and washers.

  • Exhaust and emissions
    7% of testsRough price £100–£1,200

    At the viewing: Look for black soot in the tailpipe, listen for blowing from the exhaust and check for engine or DPF warning lights.

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Other years

YearMOT testsMost flagged
20161,248Tyres 31%
20154,852Tyres 30%
20144,786Tyres 31%
20134,481Tyres 31%
20125,482Tyres 30%
20112,481Brakes 30%
20102,039Brakes 31%
20083,124Suspension 35%
20073,390Suspension 37%
20063,487Suspension 36%
20054,447Suspension 36%
20042,774Suspension 38%
20031,531Lights and electrics 35%
20021,637Brakes 35%
20011,856Brakes 33%
20001,515Lights and electrics 35%

Where this comes from: the DVSA's anonymised results for every MOT test in Great Britain in 2025, counting tests of 2009 Mercedes-Benz SLKs registered in 2009. "Flagged" includes advisories, so it isn't the same as a fail rate. How we score