Mazda 3 III vs Mazda 3 IV: which is more reliable?
According to the MotorFiable Score, the Mazda 3 IV (6.6/10) has fewer serious documented faults than the Mazda 3 III (6.2/10), mainly because of their engines.
| Item | Mazda 3 III | Mazda 3 IV |
|---|---|---|
| Segment | Compact | Compact |
| Years | 2013–2019 | 2019–today |
| MotorFiable Score | 6.2 out of 10 | 6.6 out of 10 |
| Engine score | 6.0/10 | 6.6/10 |
| Most recommended engine | Skyactiv-G · Buy | Skyactiv-G · Buy |
| Score for the rest of the car | 6.5/10 | 6.7/10 |
| Suspension | 6.8 out of 101 faultLow severity | 7.9 out of 100 faults |
| Electrical system | 8.6 out of 101 faultMedium severity | 8.6 out of 101 faultMedium severity |
| Electronics and infotainment | 8.9 out of 101 faultLow severity | 8.9 out of 101 faultHigh severity |
| Climate control | No documented faults | 9.3 out of 101 faultMedium severity |
| Bodywork and interior | 7.6 out of 101 faultCritical severity | 8.3 out of 101 faultLow severity |
| Airbags and safety | No documented faults | 7.1 out of 101 faultCritical severity |
Scores out of 10: the higher, the fewer serious documented faults. How we calculate them
Main faults of the Mazda 3 III
Outside the engine
- Critical severityFrequency: OccasionalBodywork and interiorFuel leak caused by a broken tank vent pipeYes: some Mazda3 BM cars built in 2015 were recalled because the plastic joint between the fuel tank and its vent pipe can crack and let vapour or fuel escape, with a risk of fire near a source of ignition.
- Medium severityFrequency: OccasionalElectrical systemWiper failure caused by corrosion in an electrical connectorYes: Mazda recalled Mazda3 BM cars built between July 2015 and July 2017 because a deposit of metal particles in a connector can interrupt the current feeding the wiper motor and leave the wipers not working.
- Low severityFrequency: CommonElectronics and infotainmentInfotainment system freezes and loses Bluetooth, USB or navigationIt is one of the most repeated complaints about the Mazda3 BM: the MZD Connect infotainment system can freeze, restart on its own or lose its Bluetooth, USB, GPS or radio connection. A German used-car guide independently confirms that the system can feel slow in daily use.
In their engines
- High severityFrequency: CommonSkyactiv-DOil dilution with diesel during DPF regenerationsOn the Skyactiv-D (1.5, 1.8 and 2.2), particulate filter regenerations can let diesel into the sump and raise the oil level. Mazda accepts some dilution as normal, but on short urban journeys the expected margin can be exceeded and harm the lubrication of the turbo and the camshaft.
- High severityFrequency: CommonSkyactiv-DTurbo wear or failure from lack of lubricationThe two-stage sequential turbo of the 2.2 Skyactiv-D appears as one of the most cited faults by CX-5, Mazda6 and Mazda3 owners, especially when the oil has lost lubricating ability through dilution or when the camshaft on 2013-2014 units sheds metal particles.
- Critical severityFrequency: OccasionalSkyactiv-DOil pump chain breakage and camshaft wearIn the worst cases, lack of lubrication on the 2.2 Skyactiv-D (from diluted or degraded oil) can end up breaking the oil pump chain or damaging the camshaft, cutting off oil pressure and potentially destroying the engine; fiches-auto.fr documents this breakage on the CX-5, the Mazda6 and the Mazda3.
Main faults of the Mazda 3 IV
Outside the engine
- Critical severityFrequency: OccasionalAirbags and safetySmart Brake Support can brake the car unintentionally while drivingOn cars built between November 2018 and October 2019, an unintended activation of the Smart Brake Support automatic braking system can stop the car unexpectedly while it is moving, with a risk of the vehicle behind running into it. Mazda inspects it free of charge at an official dealer.
- Medium severityFrequency: OccasionalElectrical systemThe m-hybrid system can drain or damage the 12 V batteryOn versions with the m-hybrid mild-hybrid system, some owners describe a sudden drain of the 12 V battery with very low mileage and a progressive loss of charge that forces them to replace it sooner than expected; there is no manufacturer campaign acknowledging the problem as systemic.
- High severityFrequency: RareElectronics and infotainmentThe rear-view and 360° cameras may not show an image on the screenOn cars built between June and September 2023, incorrect processing in the camera control module can stop the image from the rear, side or 360° monitor camera appearing on the central screen. Mazda fixes it by updating the module at an official dealer.
In their engines
- High severityFrequency: CommonSkyactiv-DOil dilution with diesel during DPF regenerationsOn the Skyactiv-D (1.5, 1.8 and 2.2), particulate filter regenerations can let diesel into the sump and raise the oil level. Mazda accepts some dilution as normal, but on short urban journeys the expected margin can be exceeded and harm the lubrication of the turbo and the camshaft.
- Medium severityFrequency: CommonSkyactiv-DCarbon build-up in the intake, EGR and injectorsUrban use and short journeys encourage carbon build-up in the intake manifold, EGR valve and injectors of the Skyactiv-D, with loss of power and uneven running; it is documented on the CX-5, the Mazda6, the Mazda3, the CX-3 and the CX-30.
- Medium severityFrequency: OccasionalSkyactiv-GIntake shut-off valve software issue and engine stallingOn Mazda3 BM/BN units built up to 4 July 2018, incorrect ECU programming can deposit soot on the intake shut-off valve to the point of suddenly stalling the engine; Mazda fixed it with a software update.