2021 Mazda 3: What to check before buying

Oil disappears with no visible leak. A low oil level warning often appears between 4,600 and 8,990 miles, well before the next scheduled change. Owners describe adding a quart every 1,500 to 4,000 miles, and several reports involve the 2.5 liter turbo. Dealers often confirm the consumption and point to a Mazda service bulletin. They offer no repair, though, and tell owners to monitor it or call it normal. One driver had to stop after a low oil pressure warning, and owners worry about the engine seizing while driving.

The battery drains and the car will not start, sometimes again within days, even after one or two battery replacements. Dealers often confirm the drain but cannot find the cause. One proposed replacing the rear wiring harness. Some cars stall while driving, showing engine malfunction or low 12-volt charge warnings, and need a jump start. Some cars are towed to the dealer repeatedly. Other reports describe the display or USB cutting out, start key errors, a low oil pressure warning that will not clear, and a car bouncing while stopped.

Windshield glass has wavy, distorted areas on the driver side, the passenger side, or across both. Drivers report eye strain, headaches, dizziness and fatigue on long drives, plus poor visibility at night. Some notice it at delivery, including certified pre-owned buyers. Replacement windshields often show the same distortion. Mazda has told dealers some distortion is normal for this design and has pushed back on further replacements. Separate reports describe a tiny chip spreading into a long crack and sunroof glass blowing outward at highway speed.

The car fails to stop or surges forward at low speed even with the brake pedal pressed. These reports include 3 crashes, in a parking garage, at a red light, and while shifting from a standstill. No warning light appears beforehand. Automatic emergency braking also slams on with nothing ahead, in one case causing a neck injury. Another driver saw a critical brake system malfunction message that no shop could explain. Dealers report no permanent fix. Rear brakes also wear out unusually fast.

The transmission fails suddenly in some cars. The car surges, accelerates in bursts, or loses power on the highway before engine and transmission warning lights come on. In another case, a rough-running engine was blamed on a corroded wiring harness, and the dealer then called for a new transmission. Other complaints describe the same oil consumption seen under the engine category, with low oil warnings before the scheduled change. Owners cite a valve stem seal settlement and a service bulletin. Battery drain after a new battery, random lock and liftgate behavior, and poor fuel economy also appear.

The car speeds up on its own. Reports include 2 crashes, one into a brick pillar and one into an apartment building, and one caused neck and back injuries. In the second case, pressing the brake did not stop the car while parking. Adaptive cruise control also accelerates hard when the car ahead leaves the lane, briefly going above the set speed. One sudden lunge in a turn was followed by a transmission error and a code for a stuck shift solenoid.

Binding at highway speed, followed by a sudden release, makes small lane corrections jerky and leads to overcorrecting. Owners say the symptoms match a Mazda service bulletin that covers only vehicles through model year 2020. One dealer planned to relubricate the worm gear in the steering assembly. A separate report describes a burst of warnings, including power steering, push button start, and in-vehicle network faults. After that, the car would not start and was towed to a dealer.

Automatic emergency braking engages with nothing ahead. In one case it skidded the car to a stop in a traffic lane after a turn, and the owner later found flies on the front sensor. Rear-end collisions were avoided only because traffic behind was far enough back. In the most serious report, cruise control at 60 mph did not disengage when the driver braked approaching a light. The crash that followed injured 4 people, and no warning light appeared.