Mercedes-Benz SLK common problems and MOT failures

What usually goes wrong with a Mercedes-Benz SLK?

Known faults reported by owners, mechanics and UK buying guides, in our own words. Most apply to certain years or engines only, so check which the car has.

• Roof motors and pump

  Cars registered 2004–2011 · All engines

  The roof motors can seize if the roof stays up for long periods, and a slow roof usually means a failing pump. Both are costly.

  At the viewing: Open and close the roof several times and time it.

  Source: What Car?: used Mercedes-Benz SLK (2004-2011) reliability

• Balancer shaft and timing chain failures (early engines)

  Cars registered 2012–2016 · Early SLK 200 and 350

  Early 350 V6s can suffer balancer shaft gear failure, showing as misfires and an engine light before timing chain failure. Early 200s can wear their timing chain and cam sprocket early.

  At the viewing: Listen for rattles from cold, and check for misfires and warning lights.

  Source: What Car?: used Mercedes SLK (2011-2016) reliability

• Folding roof faults

  Cars registered 2012–2016 · All engines

  Many owners report problems with the folding hard-top: microswitches stick from lack of use, and the boot divider can jam the roof.

  At the viewing: Open and close the roof several times.

  Source: What Car?: used Mercedes SLK (2011-2016) reliability

• Leaking boot seals

  Cars registered 2004–2011 · All engines

  Boot seals fail often, letting water collect in the spare wheel well.

  At the viewing: Lift the boot floor and look for water or damp.

  Source: What Car?: used Mercedes-Benz SLK (2004-2011) reliability

• Water reaching the door modules

  Cars registered 2012–2016 · All engines

  Seals at the A-pillar and windscreen can let water reach the door control modules, affecting the locking and windows.

  At the viewing: Test the windows and locking, and look for damp.

  Source: What Car?: used Mercedes SLK (2011-2016) reliability

• Suspension bushes, broken springs and exhaust cracks

  Cars registered 2012–2016 · All engines

  Thrust arm and anti-roll bushes are weak, broken springs are increasingly common, and the exhaust Y-section cracks.

  At the viewing: Listen over bumps and look underneath.

  Source: What Car?: used Mercedes SLK (2011-2016) reliability

• Rear subframe corrosion (older cars)

  Cars registered 2012–2016 · Older cars

  Older cars can rust on the rear subframe, which can fail an MOT.

  At the viewing: Look at the rear subframe.

  Source: What Car?: used Mercedes SLK (2011-2016) reliability

Common Mercedes-Benz SLK MOT failures to check

Parts flagged at MOT well above the usual rate for cars the same age, for each fuel on its own. From the DVSA’s results for every MOT done in Great Britain during 2023–2025.

Petrol

• Wheel bearings

  up to 6× usual

  Stands out on cars registered in 2012, 2013, 2014, 2015 and 2016.

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

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

• Link ball joint covers

  up to 3.4× usual

  Stands out on cars registered in 2012, 2013 and 2014.

  Rough price £60–£150 (one joint) ClickMechanic

  At the viewing: Listen for knocking over bumps and check the rubber boots behind the wheels aren't split.

Diesel

• Wheel bearings

  up to 6× usual

  Stands out on cars registered in 2012, 2013, 2014, 2015 and 2016.

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

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

• Link ball joint covers

  up to 4× usual

  Stands out on cars registered in 2012, 2013, 2014 and 2015.

  Rough price £60–£150 (one joint) ClickMechanic

  At the viewing: Listen for knocking over bumps and check the rubber boots behind the wheels aren't split.

• Wheels

  up to 2× usual

  Stands out on cars registered in 2014 and 2015.

  Rough price £70–£150 our estimate

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

• Ball joint dust cover

  up to 2× usual

  Stands out on cars registered in 2012 and 2013.

  Rough price £60–£150 (one joint) ClickMechanic

  At the viewing: Listen for knocking over bumps and check the rubber boots behind the wheels aren't split.

Mercedes-Benz SLK MOT pass rate by year

Of the years since 2005 with plenty of MOT tests, the 2011 Mercedes-Benz SLK did best (77% passed first time, 15 points above all 2011 cars) and the 2016 did worst (84%, 7 points above all 2016 cars). Older cars fail more, so compare each year with all cars registered the same year.

Questions to ask the seller before buying a Mercedes-Benz SLK

Ask before you travel to see it. A seller who knows the car will have answers, and receipts.

1. Has the roof had any work?
2. Has the timing chain or balancer shaft been replaced?
3. Has the roof had any repairs?
4. Any recent work on the wheel bearings? (Flagged at MOT 6× as often on the Mercedes-Benz SLK as on other cars the same age.)
5. Any recent work on the transmission oil leaks? (Flagged at MOT 4.2× as often on the Mercedes-Benz SLK as on other cars the same age.)
6. Any recent work on the rigid brake pipes? (Flagged at MOT 2.5× as often on the Mercedes-Benz SLK as on other cars the same age.)