2015 Mazda 6 diesel: common problems and MOT failures

What goes wrong more than usual on a 2015 Mazda 6 diesel?

Parts flagged at MOT more often on the 2015 Mazda 6 diesel than on all cars registered in 2015.

• Suspension arm bushes and joints1.9× usual
  Mazda 6

  11.2% All 2015 cars

  5.8%

  Failed outright at MOT: 0.9%, against 1.2% of all 2015 cars. The rest were advisories or minor defects.

  Rough price £120–£180 (one arm) ClickMechanic

  At the viewing: Listen for clunks over bumps and feel for the steering wandering. Worn arm bushes show as cracked rubber near the wheels.

• Rigid brake pipes3.3× usual
  Mazda 6

  6.6% All 2015 cars

  2%

  Failed outright at MOT: 1.1%, against 0.3% of all 2015 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.

• Suspension arm5.4× usual
  Mazda 6

  3.8% All 2015 cars

  0.7%

  Failed outright at MOT: 0.1%, against 0.1% of all 2015 cars. The rest were advisories or minor defects.

  Rough price £120–£180 (one arm) ClickMechanic

  At the viewing: Listen for clunks over bumps and feel for the steering wandering. Worn arm bushes show as cracked rubber near the wheels.

• Ball joint1.9× usual
  Mazda 6

  5.6% All 2015 cars

  3%

  Failed outright at MOT: 3.4%, against 1.7% of all 2015 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.

• Sub-frame3.6× usual
  Mazda 6

  3.2% All 2015 cars

  0.9%

  Failed outright at MOT: 0%, against 0% of all 2015 cars. The rest were advisories or minor defects.

  Rough price £300–£1,000 our estimate

  At the viewing: Look underneath at the frame the suspension bolts to. Flaky rust or holes are expensive to fix.

Common 2015 Mazda 6 diesel MOT failures and advisories

The share of 2015 Mazda 6 diesel MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.

• Tyres
  30% 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
  29% 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.

• Lights and electrics
  10% 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
  6% of testsRough price £15–£250

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

• Seats and seatbelts
  3% of testsRough price £80–£250

  At the viewing: Pull each seatbelt sharply. It should lock, and retract cleanly.

Known faults on the 2015 Mazda 6 diesel

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.

• Diesel in the oil (particulate filter)

  Diesel

  If the engine is switched off during particulate filter cleaning, fuel can get into the oil and raise the level, which can damage the engine.

  At the viewing: Check the oil isn’t above the max mark and ask what journeys it does.

  Source: What Car?: used Mazda 6 (2013-2022) reliability

• Airbag inflator and boot strut recalls

  All engines

  Driver’s airbag inflators can rupture after long exposure to humidity and must be replaced, and boot struts were recalled in 2017.

  At the viewing: Ask a Mazda dealer to confirm the recalls were done.

  Source: What Car?: used Mazda 6 (2013-2022) reliability

• Warped brake discs

  All engines

  It can be hard on its brake discs, causing vibration under braking.

  At the viewing: Brake firmly from speed and feel for shaking.

  Source: What Car?: used Mazda 6 (2013-2022) reliability

Questions to ask the seller before buying a 2015 Mazda 6 diesel

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

1. Does it do regular motorway runs?
2. Any recent work on the suspension arm bushes and joints? (Flagged at MOT 1.9× as often on the 2015 Mazda 6 diesel as on other cars the same age.)
3. Any recent work on the rigid brake pipes? (Flagged at MOT 3.3× as often on the 2015 Mazda 6 diesel as on other cars the same age.)
4. Any recent work on the suspension arm? (Flagged at MOT 5.4× as often on the 2015 Mazda 6 diesel as on other cars the same age.)
5. Can I see the service history and receipts for any big jobs?