2012 Mazda 3 diesel: common problems and MOT failures

What goes wrong more than usual on a 2012 Mazda 3 diesel?

Parts flagged at MOT more often on the 2012 Mazda 3 diesel than on all cars registered in 2012.

• Sub-frame4.9× usual
  Mazda 3

  16.5% All 2012 cars

  3.4%

  Failed outright at MOT: 0.2%, against 0.2% of all 2012 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.

• Ball joint3.5× usual
  Mazda 3

  18.1% All 2012 cars

  5.2%

  Failed outright at MOT: 10.1%, against 2.9% of all 2012 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.

• Anti-roll bar link joints4.7× usual
  Mazda 3

  14.2% All 2012 cars

  3%

  Failed outright at MOT: 3.1%, against 1.1% of all 2012 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.

• Suspension arm6× usual
  Mazda 3

  11.4% All 2012 cars

  1.9%

  Failed outright at MOT: 0.1%, against 0.2% of all 2012 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.

• Headlights1.7× usual
  Mazda 3

  6.9% All 2012 cars

  4%

  Failed outright at MOT: 2.2%, against 2.7% of all 2012 cars. The rest were advisories or minor defects.

  Rough price £40–£400 our estimate

  At the viewing: Check both headlights on dipped and full beam, and look for cloudy or cracked lenses.

Common 2012 Mazda 3 diesel MOT failures and advisories

The share of 2012 Mazda 3 diesel MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.

• Suspension
  53% 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.

• Tyres
  38% 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.

• Brakes
  30% 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
  25% 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
  9% 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
  6% 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 2012 Mazda 3 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.

• Particulate filter additive and injectors (1.6 diesel)

  1.6 diesel

  The 1.6 diesel's particulate filter uses an Eolys additive that needs topping up, usually around 75,000 miles, and its injectors can fail, causing power loss and warning lights.

  At the viewing: Ask whether the additive has been topped up, and watch for warning lights.

  Source: What Car?: used Mazda 3 (2009-2013) reliability

• DPF warning lights (diesel)

  Diesel

  Particulate filter warning lights shouldn't be ignored, as they can mean costly repairs.

  At the viewing: Make sure no DPF warning shows.

  Source: What Car?: used Mazda 3 (2009-2013) reliability

Questions to ask the seller before buying a 2012 Mazda 3 diesel

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

1. Has the DPF additive been topped up, and have the injectors been replaced?
2. Any recent work on the sub-frame? (Flagged at MOT 4.9× as often on the 2012 Mazda 3 diesel as on other cars the same age.)
3. Any recent work on the ball joint? (Flagged at MOT 3.5× as often on the 2012 Mazda 3 diesel as on other cars the same age.)
4. Any recent work on the anti-roll bar link joints? (Flagged at MOT 4.7× as often on the 2012 Mazda 3 diesel as on other cars the same age.)
5. Can I see the service history and receipts for any big jobs?