2018 Mazda 3 diesel: common problems and MOT failures

What goes wrong more than usual on a 2018 Mazda 3 diesel?

Parts flagged at MOT more often on the 2018 Mazda 3 diesel than on all cars registered in 2018.

• Brake pads1.8× usual
  Mazda 3

  19.9% All 2018 cars

  10.9%

  Failed outright at MOT: 4.3%, against 2% of all 2018 cars. The rest were advisories or minor defects.

  Rough price £75–£175 (one axle) ClickMechanic

  At the viewing: Listen for squealing or grinding when braking, and look through the wheel at how much pad is left.

• Rigid brake pipes10× usual
  Mazda 3

  5% All 2018 cars

  0.5%

  Failed outright at MOT: 0.6%, against 0.1% of all 2018 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.

• Coil springs4.5× usual
  Mazda 3

  5% All 2018 cars

  1.1%

  Failed outright at MOT: 4.7%, against 0.9% of all 2018 cars. The rest were advisories or minor defects.

  Rough price £175–£400 (pair, one axle) ClickMechanic

  At the viewing: Look behind each wheel for a snapped spring coil, and listen for a clunk or twang when turning the wheel lock to lock with the car stopped.

Common 2018 Mazda 3 diesel MOT failures and advisories

The share of 2018 Mazda 3 diesel MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.

• Brakes
  32% 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
  32% 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
  11% 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.

• 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.

• Lights and electrics
  6% of testsRough price £10–£80

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

• 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 2018 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.

• Blocked particulate filter (diesel)

  Diesel

  The diesel’s particulate filter can clog on cars used only for short trips.

  At the viewing: Ask what journeys it does, and watch for a DPF warning light.

  Source: Auto Express: used Mazda 3 (Mk3, 2014-2019) review

• Infotainment glitches

  All engines

  There are some reports of glitches and lag with the infotainment and sat nav.

  At the viewing: Try the screen, sat nav and phone connection.

  Source: Auto Express: used Mazda 3 (Mk3, 2014-2019) review

Questions to ask the seller before buying a 2018 Mazda 3 diesel

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

1. Any recent work on the brake pads? (Flagged at MOT 1.8× as often on the 2018 Mazda 3 diesel as on other cars the same age.)
2. Any recent work on the rigid brake pipes? (Flagged at MOT 10× as often on the 2018 Mazda 3 diesel as on other cars the same age.)
3. Any recent work on the coil springs? (Flagged at MOT 4.5× as often on the 2018 Mazda 3 diesel as on other cars the same age.)
4. Can I see the service history and receipts for any big jobs?