Mazda CX-9 Transmission Problems

Transmission complaints by model year

Which parts fail

• Automatic transmission
  2
• Transfer case (4-wheel drive)
  2
• Driveline › Differential unit
  1

Components named in complaints (automatic and manual transmissions, CVT, axles, driveshaft, 4WD/AWD).

Mileage when the problem started

• Under 25k
  1111%
• 25k–50k
  1817%
• 50k–75k
  1313%
• 75k–100k
  2221%
• 100k–150k
  3231%
• 150k+
  77%

What owners report

I was in a parking lot and came to a stop and placed the car in reverse to back into a parking space. The back-up camera was on and I began to back into the parking space when the car suddenly lurched/jerked forward and accelerated on its own. The car jumped the parking lot median strip and I hit a tree head on. I had my seatbelt on and the airbag deployed. The car then reversed back off the median into the parking lot. I turned off the car. Insurance company will have it inspected. The vehicle is a total loss. I was injured with a large lower abdomen hematoma and airbag burns on arms, wrists, and chest as well as various bruising. I was fortunate to have not hit pedestrians who were walking in the lot or other vehicles that were parked in the lot. There were no warning lights, messages, sounds. The brake assist did not engage. It was frightening.

The vehicle was parked stationary in the driveway with the engine running for 3-5 minutes with the A/C on. The vehicle then accelerated forward into my garage causing damage. Once I entered the vehicle, both the dash and shifter displayed park. Current TCU system internal failures have been reported from the pulling of data from Mazda.

The engine cylinder head developed an internal coolant leak, allowing coolant to enter the combustion chamber. This caused engine overheating and smoke coming from the tailpipe while driving. A dealer performed a coolant pressure test confirming coolant leaking into the combustion chamber, and wet/dry compression testing on all 4 cylinders showed low and inconsistent readings consistent with cylinder head coolant intrusion (Cylinder 1: 105/125 psi, Cylinder 2: 115/125 psi, Cylinder 3: 110/175 psi, Cylinder 4: 160/190 psi). Overheating creates a risk of sudden loss of power and potential engine failure while driving, including on the highway. The problem has been confirmed and diagnosed by an authorized dealer service center, and the manufacturer's technical hotline department reviewed the diagnostic findings directly. …

The engine developed a sudden coolant leak on the rear of the engine. A warning comes up stating that the car could overheat and lose power. After a few minutes and no sign of the car overheating, the car loses power and slows down on its own. The car has not yet been seen by the dealer or a repair shop due to no appointments available. Mazda USA has issued a TSB stating the issue with the engine and they state that a design flaw causes the cylinder head to crack because of the external forces from the exhaust system over bumps. The failure appeared all of a sudden with no warning lights or indications, it just started leaking a small amount of coolant one day. Now I'm waiting for Mazda USA to tell us how they are going to remedy this issue and provide assistance. According to their TSB this affects three different vehicle models with the same 2.5L turbo engine built from 2016 to 2020.

I own a 2018 Mazda CX - 9 with only 53,300 miles. I noticed something was wrong with my engine and had no idea what the issue was. My car would not shut off immediately when I turned it off and the fan was on super high speed. The day before my appointment with my mechanic, the engine light turned on. I was stuck in a parking lot and a friend suggested I use his car to go buy coolant just in case it was needed. Sure enough, I was completely out of coolant. When my mechanic inspected the car he told me I had a coolant leak and suggested I take it to the dealer as they would know immediately what the problem was. …

My 2018 Mazda CX-9 with the SKYACTIV-G 2.5T engine has been diagnosed with a cracked cylinder head, cracked exhaust manifold, and cracked turbocharger at approximately 88,000 miles. This is a known design defect documented in Mazda TSB 01-002/23 and addressed by Customer Service Program CSP11, which extended the powertrain warranty to 10 years/120,000 miles for coolant leaks at the cylinder head. The TSB identifies exhaust manifold deformation and residual production stress as root causes of the cylinder head cracking. In my vehicle, the failure has extended to the exhaust manifold and turbocharger, both directly mounted to the cylinder head in the same high-stress zone. The turbocharger on this engine is a coolant-cooled unit. …

There was a coolant leak on my Mazda CX9 Signature with a 2.5T engine, and when driving the engine temperature started increasing slightly before taking off and turning red. I had to pull off to the side of a busy interstate road very quickly and shut the vehicle down before it overheated any more. Once I got the vehicle to the dealership, they told me it was a cracked cylinder head leaking coolant, and that it was an extremely common problem for the 2.5T mazda engines around about 60k miles, and they were actively working on one in the shop where I was for the same problem. Mazda is not currently helping with engine swap or any repairs as a result and is sticking the customer with the bill.

I was driving the vehicle on the highway when the vehicle started to overheat, lights started blinking, the car was smoking, losing power and acceleration. This car has a recall on the cyclindwr head which when cracks causing the car to loose coolant and oil. If it cracks while you're driving especially on the highway the car will immediately loose coolant and oil thus causing a very dangerous driving condition. There was no indicator prior to the failure that there was anything wrong with the car. No check engine lights, no coolant lights nothing. Prior to this happening I smelled coolant in the car cabin , took it to my mechanic who tested the coolant system and found no leak. At the time he was unaware of the known issue these cars have with the cylinder head. …