2020 Mazda CX-9 Problems and Top Issues

Our data shows that engine and electrical system issues are among the top complaints

Updated on Author: Brian Jones | Reviewer: Sergei Lemberg

The 2020 Mazda CX-9 is a three-row SUV designed for families. The company’s slogan is “driving matters,” but owners of vehicles with defective engines and faulty electrical systems are wondering how much it matters to the automaker.

Click on other model year to view more problems: 2019   2021


The most common complaints lodged with the National Highway Traffic Safety Administration (NHTSA) relate to the electrical system and engine of the 2020 Mazda CX-9. Issues include vehicles shutting off, others accelerating on their own, and engines overheating.

There are also reported problems that affect forward avoidance collision, the powertrain, structure, and visibility/wiper.

The visibility issue is one that seems to happen with a wide range of vehicles, not only Mazdas — their sunroofs explode!

In addition to complaints, there is one recall for 2020-2021 CX-9 vehicles that have faulty seats. The problem, according to Mazda, is that 8,648 CX-9 vehicles of these model years are equipped with 60/40 split bench second-row seats that may malfunction. More specifically, the left-side second-row seat may unexpectedly slide forward during a crash. If this happens, the seat can transfer excessive force onto a belted occupant, increasing their risk of injury. The internal parts of affected seats must be replaced by dealers free of charge.

2020 Mazda CX-9 Complaint Summary

Complaint CategoryNumber of Complaints
Electrical System
Forward Collision Avoidance: Automatic Emergency Braking
Power Train
Unknown Or Other

Electrical System

It can be terrifying when a vehicle suddenly stops accelerating or shuts off while driving. But there are owners of 2020 Mazda CX-9 vehicles who have experienced exactly these issues.

One owner tells how the Mazda CX-9 stopped accelerating on a freeway — “and the engine light, sensor light, and sensor warning came on.” They were, though, able to pull over.

“We turned the vehicle off, then on again, and all lights went away and we continued on. This is a safety hazard because the car would not accelerate while we were going 60 mph on the freeway.”

A Florida owner describes how the electrical system shut down and the CX-9 “shut off and coasted to a braked stop in the center lane of a 3 lane road.” There was no warning, and everything relating to the electrical system shut off. Luckily, the driver was able to restart the vehicle by shifting into Park and pressing the start button. He took the CX-9 to the dealer and was told the problem had been escalated to a national team for diagnosis. But, 10 days later, they came back and said nobody could reproduce the system shutting off or find any error codes.

“They wanted to return the car to the driver with no need for a repair. The driver spoke to the National Mazda helpline and the representative was aware of the situation. The representative reiterated that engineers had been unable to find the source of the incident in the computer logs so they could not provide a remedy. The representative offered the driver the choice of a purchase buyback and a discount on the purchase of a new car.”

This is something to remember! Even when dealers cannot find faults, this doesn’t mean there is nothing wrong with your car.


By far, the most important part of the vehicle is the engine. Any malfunction is a cause for alarm.Here is an NHTSA complaint about “uncommanded engine acceleration.” Luckily, the owner states, it didn’t result in any damage “primarily because it commenced several seconds after I began light braking while approaching a red traffic light. My immediate response was to increase brake pressure; there was no need for me to move my leg other than pressing harder with my foot. My foot had been off the accelerator for many seconds while allowing the car to slowly decelerate while coasting toward traffic stopped at a red light.”

After a mere two seconds, with the car fully stopped, “I shifted the transmission into Neutral. The engine immediately generated the noise of very high RPM. Although the dashboard includes a tachometer, I did not immediately think to look at it; instead, I turned the ignition off. A few seconds later, I shifted the transmission into Park and restarted the car which operated normally thereafter. My foot did not move off the brake pedal during any of the preceding sequences.”


An owner from Illinois had a different experience, this time with a coolant leak at the cylinder head around the exhaust manifold. A technical service bulletin (TSB) last issued in October 2023, warns of these possible leaks. Additionally, manufacturer communication 01-002-23 warns that, “There may be cracks at the stud bolt hole (1) or at the outside of the exhaust manifold flange (2) on the cylinder head.” But this NHTSA complaint states that this didn’t help.

In this case, an excessive coolant leak had led to the engine overheating and the CX-9 going into “limp mode”. The owner wasn’t able to drive faster than about 30 mph.” Mazda has repeatedly declined help with goodwill requests and any further assistance.”

Exploding Sunroofs

An owner from California tells how the CX-9 sunroof exploded outward while traveling at freeway speed. “The sound was close to a very loud pop, and not the sound of rock/debris impact. At the time of the explosion, there were no vehicles nearby and no overpasses from which an object could have dropped. The vehicle had been washed the day before and there was no visible damage to the sunroof.”

The complaint states that the sunroof and interior cover were closed when the sunroof exploded and that most of the glass blew upward. “There were three people in the vehicle at the time (driver, front seat passenger, and middle row passenger behind the driver). The two passengers were asleep and woke abruptly thinking we had been hit by something, as the explosive bang was followed by the sound of air rushing past the hole.”

So What Can You Do?

Whether you have engine, electrical, or any other recurring problems, there’s a chance you might have purchased a lemon. If you think this is the case, contact Lemberg Law and we will assess your problem free of charge.

Automakers are forced to replace, buy back, or pay cash settlements to thousands of vehicle owners every year. And they have to pay the legal bills as well. So, if you think you have a lemon, call our Helpline or fill out a contact form and we’ll see how we can help. 

Brian Jones

About the Author:

Brian Jones spent more than 30 years working as an ASE Certified Master Tech and Parts Specialist at multiple dealerships. Brian has become an authority in the industry, traveling across the country to consult for car dealerships and contributing his expertise as a writer for several major automotive publications. In his spare time, Brian enjoys working on pickup trucks, muscle cars, Jeeps and anything related to motorsports.

See more posts from Brian Jones

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