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Overall, the Mazda CX-9 midsize SUV is popular in its segment. But as with any vehicle, mechanical failures often lead to customer dissatisfaction. Since its introduction in 2007, the most common major issues for the Mazda CX-9, as tabulated by Car Complaints, include brake system problems, engine failures, and coolant system issues.

The Mazda CX-9’s engine failure

Overall, the 2012 Mazda CX-9 received the most complaints, but Car Complaints rates 2008 as the “Worst Model Year,” citing issues with the braking system as the main issue with both models. Complaints dwindled beginning with the 2017 Mazda CX-9 and appear to have remained low into 2020.

With a “Really Awful” label for Car Complaints’ severity rating of 10.0, engine failure comes in at No. 3 on Car Complaint’s list of issues with the Mazda CX-9. The most common solution for engine failure is to replace the entire engine at a typical repair cost of $5,000. Yikes.

On average, Mazda CX-9 owners with failed engines experienced that failure at 99,250 miles. While this is the most expensive and severe complaint submitted against the Mazda CX-9, it’s also the most infrequent complaint. So, the possibility of engine failure is low, but it has happened to some owners.

CX-9 brake power boost unit failure

A red Mazda CX-9 midsize SUV is parked.
The Mazda CX-9 | Mazda

The most frequent Mazda CX-9 complaint is the brake power boost unit failure. Typically, this issue occurs at 67,100 miles and is resolved by the complete replacement of the power boost unit at an average cost of $680.

Drivers experiencing a power boost unit failure may notice longer stopping distances, a brake pedal that is hard to push, and an engine stall when brakes are applied. This could be dangerous and potentially lead to an accident if not repaired immediately. The frequency of this complaint puts it at No. 2 on Car Complaints’ list with a “Pretty Bad” severity rating of 8.0.

Mazda CX-9 water pump failure

A red Mazda CX-9 midsize SUV.
The Mazda CX-9 | Mazda

No. 1 on Car Complaints’ list of Mazda CX-9 complaints with another “Really Awful” severity rating of 10.0 is water pump failure. This issue earns the top spot due to collateral damage. Often, when a Mazda CX-9 water pump fails, it leaks coolant into the engine oil and causes engine failure too.

On average this has occurred at 102,150 miles and has a typical repair cost of $3,990 for replacing the entire engine with a used one. Signals that a water pump failure is imminent include coolant leaks at the front of the car, low coolant levels, and high engine temperatures. 

Is the Mazda CX-9 midsize SUV a bad choice?

Overall, the Mazda CX-9 isn’t a bad midsize SUV. In fact, it’s beginning to compete with the best models in its segment. It isn’t perfect, but the nameplate has potential because of its value and refined cabin.

On 87 octane gasoline, the 2.5-liter turbocharged inline-four cylinder engine is somewhat underpowered for its class with 227 hp, but the CX-9 makes up for it by producing about 50 lb-ft more torque than its rivals with 310 lb-ft.

Fueling the tank with 93 octane gasoline allows the engine to make an additional 23 hp and 10 lb-ft of torque. Consumer Reports recommends avoiding the higher-priced premium fuel as the modest gains in performance are hardly noticeable. 

Is the Mazda CX-9 the most reliable model in its segment? No. Are its reliability issues concerning enough to make drivers avoid the midsize SUV? They shouldn’t be. Most popular SUV models experience some issues. The potential for a total engine failure is troubling, but it isn’t happening frequently enough for consumers to steer clear of the popular CX-9 nameplate.


What Problems Does the Mazda CX-9 Have?