2009 Mercedes-Benz C-Class petrol: common problems and MOT failures

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

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

• Rigid brake pipes2.7× usual
  Mercedes-Benz C-Class

  19.3% All 2009 cars

  7.2%

  Failed outright at MOT: 3.3%, 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.

• Ball joint1.7× usual
  Mercedes-Benz C-Class

  11% All 2009 cars

  6.4%

  Failed outright at MOT: 6.2%, against 3.4% of all 2009 cars. The rest were advisories or minor defects.

  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.

• Link ball joint covers2.5× usual
  Mercedes-Benz C-Class

  7.2% All 2009 cars

  2.9%

  Failed outright at MOT: 3.2%, against 1.7% of all 2009 cars. The rest were advisories or minor defects.

  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.

• Wheel bearings2.2× usual
  Mercedes-Benz C-Class

  4.6% All 2009 cars

  2.1%

  Failed outright at MOT: 0.5%, 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.

Common 2009 Mercedes-Benz C-Class petrol MOT failures and advisories

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

• Suspension
  36% 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
  35% 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.

• Oil and fluid leaks
  4% 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.

Known faults on the 2009 Mercedes-Benz C-Class petrol

Reported by owners, mechanics and buying guides for this model and age. Check which engine the car has, as some apply to one engine only.

• Harsh 7G-Tronic automatic

  Automatic

  Later automatics can change gear harshly, and repairs are expensive.

  At the viewing: Check changes are smooth from cold and at low speed.

  If it needs doing: Gearbox sensor or solenoid, about £200–£500. ClickMechanic

  Source: Parkers: used Mercedes C-Class 2007-2014 review

• Water pump and sensors (petrol)

  Petrol

  Water pumps can leak, and air flow or crankshaft sensors cause rough running.

  At the viewing: Look for coolant leaks and check it idles smoothly.

  If it needs doing: Water pump, about £115–£375. ClickMechanic

  Source: Parkers: used Mercedes C-Class 2007-2014 review

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

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

1. Has the gearbox been serviced?
2. Has the water pump been replaced?
3. Any recent work on the rigid brake pipes? (Flagged at MOT 2.7× as often on the 2009 Mercedes-Benz C-Class petrol as on other cars the same age.)
4. Any recent work on the ball joint? (Flagged at MOT 1.7× as often on the 2009 Mercedes-Benz C-Class petrol as on other cars the same age.)
5. Any recent work on the link ball joint covers? (Flagged at MOT 2.5× as often on the 2009 Mercedes-Benz C-Class petrol as on other cars the same age.)
6. Can I see the service history and receipts for any big jobs?