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Engine & cooling

2016 Mazda CX-9 Engine problems

Owners have filed 63 complaints about the 2016 Mazda CX-9's engine & cooling with NHTSA - 64% of all its complaints, most recently on November 3, 2025. They describe 1 crash, 0 fires and 0 injuries. Stalling, loss of power, oil consumption, overheating, head gaskets, timing chains and engine failure.

Complaints
63
Recalls
0
Crashes
1
Fires
0
Injuries
0
Deaths
0

Engine complaints

Engine & cooling

In June of 2022 I started having a strong antifreeze/engine coolant smell inside the cab of my vehicle and also outside the vehicle. I had the car checked for a radiator leak, but there wasn't one. I took my car into my local Mazda where they found that the engine coolant was leaking into the heads of the engine. Mazda kept my car for 5 months and repaired the problem, it cost me $4000 and they had added a 12 month 12,000 mile warranty for the parts. My car is a 2016 Mazda cx-9 at the time of the repair it had...

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70,430 miles on it. Now a few years later I am having the same issue with the coolant smell inside the cab and outside my vehicle, it goes into the shop for diagnosis on Monday November 10,2025. The car now has 118,000 miles on it. I had purchased an extended warranty for the car at the time of purchase but it had timed out a month before I took my car in for the first repair....please Mazda stand behind your vehicles I am a senior woman with very little income and I will not be able to pay out of pocket for this repair and I CANNOT afford a new car... I would like to get reimbursed for my out of pocket on the first repair and get my car repaired this time as well under a warranty.

Filed Incident EngineNHTSA 11697196
Engine & cooling

Engine failure with crack in the engine after a loss of coolant fluid.

Filed Incident EngineNHTSA 11632664
Engine & cooling

Head gasket leaking and caused major engine issue at 89,000 miles. Mazda has known of this issue, but refuses to recall it.

Filed Incident EngineNHTSA 11626600
Engine & cooling

While my wife was driving her 2016 Mazda Cx-9 Grand Touring on the freeway, many of the dashboard indicator lights came on warning her the engine was over heating and to pull over immediately. While she was attempting to move over to the shoulder, smoke appeared from underneath the engine hood which made it difficult to safely move over to the shoulder. She believed the car was on fire so immediately exited the vehicle along with her sister whom was pregnant. I arrived within minutes and noticed the engine...

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compartment was smoking and coolant/engine oil leaking underneath the car. The car was towed to my local Mazda dealership where I was advised days later the engine needed to be replaced due to blown head gaskets. They advised the vehicle over heated causing oil and coolant leaking from cylinder head that is warped. This repair would cost $11, 179.29. Mazda service advisor also mentioned the radiator and lower/upper radiator hoses needed to be replaced. This repair would cost $2691.28. This incident could've resulted in serious injuries or death from a known issue with these engines by Mazda. It's only a matter of time before this failed engine turns into a fatality. Do the right thing Mazda and fix these engines. Your reputation is on the line.

Filed Incident EngineNHTSA 11625077
Engine & cooling

Sudden and dramatic loss of engine coolant. Received a warning that engine was overheating, and to shut off engine. Quickly obeyed the prompt and found that most of the engine coolant had been lost due to a catastrophic failure of either the head gasket or head itself.

Filed Incident EngineNHTSA 11622599
Engine & cooling

Cylinder head coolant leak. No warning lights.

Filed Incident EngineNHTSA 11617629
SteeringElectrical systemEngine & cooling

1. What component or system failed or malfunctioned, and is it available for inspection upon request? The entire electrical system is malfunctioning. All dashboard service lights (check engine, ABS, etc.) illuminate simultaneously, causing the vehicle to stutter and shut off while driving. The vehicle is available for inspection. 2. How was your safety or the safety of others put at risk? This issue has resulted in a dangerous situation, particularly when the vehicle lost power on the highway with my young...

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children aboard. This sudden loss of control could have led to a severe accident. 3. Has the problem been reproduced or confirmed by a dealer or independent service center? Mazda's service department has not been able to reproduce the problem despite multiple visits. I have provided video evidence, but no conclusive diagnosis or resolution has been achieved. 4. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives, or others? Mazda's authorized technicians have inspected the vehicle several times, but no substantial action has been taken. The vehicle has not been inspected by police or insurance representatives. 5. Were there any warning lamps, messages, or other symptoms of the problem prior to the failure, and when did they first appear? All dashboard lights come on simultaneously without prior warning. The symptoms have been random and intermittent over the past few months. Given the ongoing risk, I request an immediate replacement of my vehicle. Please confirm receipt of this complaint and provide a plan for replacement. Thank you for your prompt attention.

Filed Incident Steering · Electrical system · EngineNHTSA 11613534
Transmission & drivetrainEngine & cooling

August 2nd I noticed a smell of Coolant coming from my car. I looked under my car and noticed it leaking green coolant. I took it to Mazda where they had it for 7 days to then give me a $6,300 estimate with possible added expenses. They diagnosed it as a cracked cylinder head and needs a gasket as well. I am a single mother and have work but I cannot afford that repair especially since Mazda is not going to honor there vehicle and what they stand by. With this issue with the coolant leak and the cracked cylinder...

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the vehicle could have overheated and go into limp mode and come to a sudden stop with my children in the car while driving on the road. I could be hit as this puts my family at risk of injury while we go to school or work. Mazda has done nothing but tell me to submit a claim with customer service which I have. I had my case manager call me once and left a voicemail and I have called multiple times and have not heard back. There was no warning of this until I found forums and other stories that this unfortunately has happened to hundreds of Mazda owners.

Filed Incident Power train · EngineNHTSA 11611282
Engine & cooling

Coolant sprayed on top of engine

Filed Incident EngineNHTSA 11603263
Engine & cooling

Our 2016 Mazda CX 9 began leaking coolant and we took it to a shop who diagnosed it as coming from the cylinder head, requiring a very expensive repair or new engine. Luckily our engine did not sieze up while driving, but it easily could have with our baby and toddler in the car. Upon searching the internet I found countless reports from other CX 9 owners who experienced the very same issue at similar mileage ~50k-70k. There is a technical service bulletin for this issue, but they have not issued a recall. This...

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very expensive repair is going to set us back significantly and is a financial burden we were not expecting from our well cared for vehicle. It seems Mazda knows about the issue and is unwilling to address it.

Filed Incident EngineNHTSA 11601041
Engine & cooling

The contact owns a 2016 Mazda CX-9. The contact stated while driving at an undisclosed speed, the check engine warning light illuminated, and the vehicle started shuddering and overheating. The vehicle was taken to an independent mechanic who diagnosed the vehicle and determined that the failure was related to a cracked head gasket. The vehicle was not repaired. The contact related the failure with the Technical Service Bulletin: 01-03/21; however, the vehicle was not included. The manufacturer was not notified of the failure. The failure mileage was approximately 92,000.

Filed Incident Engine and engine coolingNHTSA 11596496
Engine & cooling

Cracked cylinder head causing coolant to leak.

Filed Incident EngineNHTSA 11593707
Engine & cooling

2016 Mazda CX-9 is leaking coolant from exhaust side of engine cylinder head. This issue has been confirmed by a Mazda dealership in North Charleston, South Carolina. The issue first appeared shortly after replacing the water pump (performed by the same dealership). The issue is known and documents on Mazda TSB 01-002/23 - COOLANT LEAKS AT CYLINDER HEAD. The safety of my family was put at risk as there was no indication of a cracked head until there was coolant leaking on the driveway. Should the car have...

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overheated without the indication of a coolant leak, the car would have been placed in to limp mode. Prior to the leak, there were no warning lamps or messages indicating the issue. Further, the Mazda dealership did not detect the issue at the time of replacing the water pump.

Filed Incident EngineNHTSA 11592348
Engine & cooling

The contact owns a 2016 Mazda CX-9. The contact stated that while driving at an undisclosed speed, the vehicle stalled. Several unknown warning lights illuminated. The contact stated after the vehicle cooled off, the was able to be restarted. The contact checked under the vehicle and stated that there was coolant leaking on the ground. The vehicle was taken to an independent mechanic, where it was diagnosed with a coolant leak behind the engine. The vehicle was not repaired. The contact related the failure to...

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Technical Service Bulletin: 01-002/23. The dealer referred the contact to the manufacturer for assistance. The contact was unable to reach the manufacturer for assistance. The failure mileage was unavailable.

Filed Incident Engine and engine coolingNHTSA 11591593
Engine & cooling

Vehicle had a horrible coolant leak at the rear of the engine to find out the engine has a weak cylinder head and is known to break and leak coolant. The vehicle will need a new cylinder head or engine replacement.

Filed Incident EngineNHTSA 11590677
Engine & cooling

A month ago, I experienced a coolant leak at the back of the engine compartment. Upon researching I found that the head was prone to crack at the turbo and produce the leak. I took to my dealer, and they confirmed that it was in fact a cracked head causing the coolant leak. They also confirmed it was a known Mazda problem on the 2016 and newer 2.5 liter turbo engines. The dealer fixed four in the last month and one on a car their salesman purchased that the head failed at only 2000 miles. I was quoted a cost of...

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$5965 for cylinder head replacement. It seems extremely excessive for a new cylinder head and a more appropriate price for a completely new motor. If this is a known defect on this motor no matter the miles, it seems Mazda should correct this problem in or out of warranty.

Filed Incident EngineNHTSA 11589984
Engine & cooling

Engine head cracked. Known problem with a tsb issued

Filed Incident EngineNHTSA 11588715
Engine & cooling

My car has a cracking cylinder head and is leaking coolant.

Filed Incident EngineNHTSA 11587338
Engine & cooling

2016 Mazda CX-9 2.5L Turbo Touring with 93,197 miles. In September of 2022, I noticed a sweet smell coming from the engine bay after coming home from work. I took my car to my mechanic on 9/30/2022 for an oil change and asked if they could figure out the "sweet smell" coming from the engine bay. When they were doing the oil change, they checked for leaks and noticed that coolant was leaking from cylinder head. Since it was out of warranty, I had my mechanic repair the issue. Which resulted in a complete cylinder...

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head replacement. This is a know issue by Mazda and there is lots of documentation online for this as well. There has since been updated parts to repair this issue, but this should be a recall covered by Mazda. Cause this repair cost me $5,700 out of pocket.

Filed Incident EngineNHTSA 11585709
Engine & cooling

We noticed anti-freeze leaking from our car a couple of days ago and immediately brought the car to our local mechanic. The mechanic determined that one of the cylinder heads in the engine was cracked and was leaking anti-freeze. He said the car was unsafe to drive. He also told us that a TSB had been issued by Mazda for this problem ( Bulletin No 01-002/23, issued 02/10/23). This bulletin states "Residual stress generated during production in the cylinder head material may be greater than expected. The external...

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force from the exhaust system when driving over bumps may cause unexpected force to certain areas of the cylinder head". Had we not noticed the leak, the engine could have overheated, causing the engine to seize at any time, any place. which could have led to a dangerous accident. An accident that could have occurred on a major highway and could have involved other vehicles as well. Our car has just under 80,000 miles, has been well maintained and garage kept. I do not understand why a manufacturing defect such as this - which could lead to engine failure is not a mandatory recall by the manufacturer. We should have been warned that this could happen and mazda should be responsible for the cost of the repair. It is an engineering design flaw of the vehicle!

Filed Incident EngineNHTSA 11582438
Acceleration & cruise controlEngine & coolingFuel system

Vehicle "surges" at idle. 300-500 RPMS at a time. Sometimes the brakes hold and sometimes not. Have nearly been in 3 collisions the last 2 days because of this issue. The ECM codes indicate throttle body or TPS issue, both of which have been unfounded. Vehicle has 63,000 miles. Researching this topic online found that many others have had this issue with no associated safety recalls noted. I am hoping to bring light to this so someone doesn't have to be injured or killed to have this rectified.

Filed Incident Vehicle speed control · Engine · Fuel / propulsion systemNHTSA 11575368
Engine & cooling

Cylinder head had a crack in it and had to be replaced.

Filed Incident EngineNHTSA 11570347
Engine & cooling

The car started to overheat so we added coolant and then the car started to stall had our mechanic look at it and he said the head gasket needs to be replaced. How is this not a recall

Filed Incident EngineNHTSA 11565213
Engine & cooling

The intercooler failed or failed cylinder head causing coolant leaking into the exhaust side and cause the engine to over heat.

Filed Incident EngineNHTSA 11564442
Engine & cooling

Engine is leaking coolant. Took the car to Horne Mazda of Avondale dealership for inspection, was told coolant is leaking from cylinder head. Was told the engine overheated and both cylinder head and cylinder block warped and will need to replace the engine. I feel my safety and others were at risk because the car could have lost power and stalled in the middle of roadway at any time due to there was no symptoms of my car engine overheated, car was running as normal, no check engine light, coolant temperature...

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gauge did not show it was overheating, no sign of engine loosing power, no smoke from under the hood, no sweet smell or any indication engine is loosing coolant and overheating while driving. It appears to be a slow leak because coolant reservoir still have coolant above minimum level. First sign of coolant leak was notice during first week of October 2023 when small amount of green fluid was found on garage floor, took car to dealer on Oct.12.2023 for inspection. MazdaUSA refused to cover engine replacement under paid Mazda Extended Confidence warranty (MEC), blaming it's owners fault for operating car while engine overheated and refused to provide written copy of inspection details.

Filed Incident EngineNHTSA 11560271

Mazda CX-9 engine complaints by year

CX-9 engine problems, every year

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Source: U.S. National Highway Traffic Safety Administration (NHTSA) complaints and recalls, checked . Complaints are owners' own reports and are not verified. How we use the data

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