2009 Mercedes-Benz S-Class: common problems and MOT failures

What goes wrong more than usual on a 2009 Mercedes-Benz S-Class?

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

• Rigid brake pipes2.3× usual
  Mercedes-Benz S-Class

  17.3% All 2009 cars

  7.5%

  Failed outright at MOT: 2%, 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.

• Wheel bearings3.5× usual
  Mercedes-Benz S-Class

  7.7% All 2009 cars

  2.2%

  Failed outright at MOT: 0.7%, 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.

• Flexible couplings40× usual
  Mercedes-Benz S-Class

  4% All 2009 cars

  0.1%

  Failed outright at MOT: 0.3%, against 0% of all 2009 cars. The rest were advisories or minor defects.

  Rough price £150–£1,000 our estimate

  At the viewing: Check the sills, wheel arches and underneath for rust, and look along the panels for uneven gaps or paint.

Common 2009 Mercedes-Benz S-Class MOT failures and advisories

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

• Brakes
  37% 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
  25% 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.

• Suspension
  24% 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.

• Lights and electrics
  20% of testsRough price £10–£80

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

• Oil and fluid leaks
  17% of testsRough price £80–£600

  At the viewing: Look under the engine and on the ground where the car is usually parked for fresh oil or fluid.

• Wipers, windscreen and mirrors
  8% of testsRough price £15–£250

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

Questions to ask the seller before buying a 2009 Mercedes-Benz S-Class

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

1. Any recent work on the rigid brake pipes? (Flagged at MOT 2.3× as often on the 2009 Mercedes-Benz S-Class as on other cars the same age.)
2. Any recent work on the wheel bearings? (Flagged at MOT 3.5× as often on the 2009 Mercedes-Benz S-Class as on other cars the same age.)
3. Any recent work on the flexible couplings? (Flagged at MOT 40× as often on the 2009 Mercedes-Benz S-Class as on other cars the same age.)
4. Can I see the service history and receipts for any big jobs?