Mazda CX-9 engine failure problems

Filed Oct 31, 2026 · Engine · FL

**the federal safety agency VEHICLE SAFETY COMPLAINT – ENGINE FAILURE AND UNAVAILABLE REPLACEMENT PART** I am filing this complaint regarding serious engine problems with my 2016 Mazda CX-9 equipped with the 2.5L SKYACTIV-G Turbo engine. My vehicle experienced significant engine problems, including overheating, diagnostic trouble codes P0014 (exhaust camshaft timing/VVT system performance) and P0303 (cylinder 3 misfire). Following diagnosis, the cylinder head was found to be cracked, requiring machining and replacement of the timing kit. Despite these extensive repairs and expenses, the vehicle continues to have unresolved engine problems, including rough idling. The vehicle has not been fully repaired because I cannot obtain the exhaust-side Variable Valve Timing (VVT) actuator required to complete the repair. I have been unable to locate this component, and Mazda USA has indicated that the part is not available through its U.S. or Canadian parts network. This leaves me with a vehicle that cannot be properly repaired due to the apparent unavailability of a critical engine component. I find it unacceptable that an essential engine component for a Mazda vehicle cannot be sourced through the manufacturer or its authorized parts network. The situation has resulted in significant financial hardship, prolonged vehicle downtime, and the inability to restore my vehicle to proper operating condition. I am concerned that the underlying engine and VVT-related problems may represent a broader safety and reliability issue affecting other owners of 2016 Mazda CX-9 vehicles equipped with the 2.5L turbocharged engine. I respectfully request that the federal safety agency investigate the reported engine problems, including overheating, cylinder-head cracking, VVT actuator failures, and the availability of replacement components. I also ask that the federal safety agency determine whether these conditions represent a safety defect that warrants further investigation or corrective action by Mazda.

Filed Sep 17, 2026 · Engine · 124,000 miles · CT

While driving at highway speed in heavy rain the oil light suddenly came on followed within 30 seconds by an urgent need to immediately stop the car due to overheating. There was no radiator fluid left due to the sudden and catastrophic structural failure caused by a known manufacturing defect. Mazda calls it csp-11. They did NOT do a recall even though a situation such as this is clearly life-threatening. They offer an extended warranty to fix the problem fully up to 120,000 miles. Our car has 124,000 miles. Two months ago it would have been fully repaired at no cost but now they want in excess of 11 THOUSAND DOLLARS. I have spoken to more than 6 people in customer service, 2 supervisors, and they are ADAMANT they will not cover one single penny of repair even though this was not due to wear and tear, but due to a known and recognized manufacturing defect which they have since corrected in newer cars. First, this should have been a full recall since having this happen with no warning is without a doubt life threatening. If an inexperienced teenager had been driving and their engine suddenly seized, they likely would have died, and taken adjacent cars with them. Second, why is this limited extended warranty allowed, it is arbitrary and capricious to say they will fix their mistake up to 120,000 miles but then in an 8-year-old car they will pay nothing? Prior to this there was no advance warning, no fluid leak, and the car had been serviced regularly without any mechanic noticing anything. 3/14/26 repair rear brake pads/rotors 113,896 miles 7/10/26 oil change/tire rotation 123,544 miles 8/7/26 Catastrophic failure due known manufacturing defect csp-11. Brought to Mazda dealer and they confirmed the hole in engine caused by this defect that has an extended warranty. Car still sitting at dealership a month later, now, like a brick, because who has $11,000 in their pocket?

Filed Sep 15, 2026 · Engine · PA

My 2018 Mazda Cx-9 equipped with the skyactiv-g 2.5T developed a serious cylinder-head/cooling-system failure. The vehicle began to lose coolant with no apparent external leak and subsequently displayed and engine -overheating warning. It continued to lose coolant after a flush. The Mazda dealership inspected the vehicle and diagnosed a warped cylinder head; I was also advised that the engine oil was milky, indicating coolant contamination. The affected component is the engine cylinder head/cooling system. This condition created a safety concern because loss of coolant and overheating can lead to severe engine damage or engine failure and potentially leave the vehicle disabled while driven. Mazda has formally documented a cylinder head coolant leak condition in certain 2016-2020 CX-9 2.5T, including cracks around the cylinder head, exhaust manifold area, and states that the cylinder hear/exhaust manifold gasket design was modified to address the condition. Mazda then established customer service program CSP11, extending coverage for the specific cylinder head coolant leak condition to 10 years/120,000 miles, whichever comes first. The dealer has confirmed and inspected my vehicles condition, and Mazda customer experience has also review the matter after I provided the TSB and CSP11 information. Mazda has declined financial assistance because my vehicle falls outside the applicable coverage period and has stated that its decision is final. I am submitting this complaint because I believe this documented cylinder head failure may represent a significant safety/reliability concern for other CX-9 owners, particularly if the condition develops shortly after the 10 year /120, 000 mile coverage limit. I believe and should be made aware of the potential for coolant loss, overheating, and engine damage and that the federal safety agency should review the scope and safety implications of this condition.

Filed Aug 8, 2026 · Engine · IN

I was driving home from work and may car started overheating out of nowhere. I was stuck in traffic and white smoke was exiting my exhaust. I pulled over and all of my coolant leaked out of my car. Took it the shop and they said I had a cracked head and need a whole new engine. I seen that there was a warranty sent out for a problem with an exhaust manifold issue leaking coolant and that is exactly what caused my problem. I contacted Mazda and they said there is nothing they can do. I will have to hire a lawyer and file a class action lawsuit. I never recieved anything from Mazda regarding the issue. They should be paying for my car. I had zero issues until the day it faulted out. I am outraged that I had a great car then something that Mazda knew about cause me an issue.

Filed Jul 23, 2026 · Engine · RI

1) What component or system failed or malfunctioned: On 6/12/2026 While drive on the highway with our daughter in the car and we experienced a high speed stall. The engine failed and we lost power. We barely got the car of the highway and coasted into a parking lot. 2) Life threating for Father, Mother and daughter and other drivers on the highway. 3) The Mazda dealer stated they were unable to reproduced problem. The diagnostic report showed few random misfired on two cylinders 2 & 3. Autozone detected codes P0300 with Secondary DTCs U0442-00 4) There car was only inspected by the dealer. The vehicle has not been inspected by Mazda the manufacturer. We requested Mazda to escalate this to the District Service Manger and to open hotline call with Mazda corporate but both of these were denied. All our service has been performed at Mazda dealer, including oil changes. We have always received a video of them working on our car with a detailed summary of what done. We did not receive the video or diagnostic report for this issue. 5) There were no warning lamps, no messages or other symptoms of the problem prior to the failure.

Filed Jul 15, 2026 · Engine · CA

The cylinder head on this 2018 Mazda CX-9 (Skyactiv-G 2.5T engine) cracked, allowing engine coolant to leak and intermix with engine oil, causing loss of coolant and catastrophic engine failure. The vehicle became undriveable in the first week of November 2025 at approximately 125,019 miles and has remained inoperable since; it was not in a crash and had to be towed. This matches a known, documented defect on Mazda's Skyactiv-G 2.5T engine: coolant leakage at the cylinder head near the exhaust manifold, leading to overheating and engine failure. Mazda issued technical service bulletin(s) addressing cylinder-head cracking and coolant intrusion, revised the cylinder-head casting (a superseding part number), and extended warranty coverage (program CSP11) for this specific concern. This vehicle fell just past the mileage cap of that extension. Safety risk: a cracked cylinder head causing coolant loss and engine overheating can produce sudden loss of engine power and overheating if it occurs while driving. No crash, fire, or injury resulted in this case. A formal dealer diagnosis is pending; the failed engine/cylinder head is being preserved and is available for inspection on request.

Filed Jul 10, 2026 · Engine, Transmission · KY

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. Warning symptoms (overheating codes and visible tailpipe smoke) first appeared at the time the vehicle was brought in for diagnosis. The manufacturer has an active technical service bulletin addressing cylinder head coolant leaks on this engine and model, along with a related warranty extension program, but has denied coverage for this repair on the basis that the leak is internal rather than external.

Filed Jun 18, 2026 · Engine · VA

My 2019 Mazda CX-9 (VIN [XXX]) suffered catastrophic cylinder head failure on the SKYACTIV-G 2.5T engine at approximately 124,000 miles. The failure is consistent with Mazda TSB 01-013/21 (and successors 01-007/22, 01-010/24), in which Mazda acknowledged that cylinder heads on this engine can crack at the stud bolt hole and exhaust manifold flange due to manifold deformation and residual production stress. The first warning came in mid-May 2026, when the engine temperature warning illuminated during normal driving. An independent mechanic replaced the thermostat. The warning returned within a week, and the thermostat was replaced a second time with a higher-quality part. Four to five days later, the warning returned alongside more severe symptoms: the vehicle began jerking while in motion, a strong coolant-burning smell developed, and smoke was visible from the exhaust pipe upon shutdown. The vehicle became undriveable, had to be left at the failure location, and was towed. Safety risk: The jerking compromised vehicle control in traffic. Upon shutdown, smoke and burning coolant odor created fire and fume-exposure risks. Had this failure occurred at highway speeds or in heavy traffic, the sudden loss of engine power and erratic behavior could have caused a serious collision. Family members were in the vehicle during several escalating events. Confirmation: The vehicle was towed to an authorized Mazda dealership, where Mazda-certified technicians confirmed in writing that it is exhibiting the exact defect described in TSB 01-013/21 and that complete engine replacement is required. The diagnosis is formally documented and has been communicated to Mazda's warranty team. Mazda Customer Experience has been engaged since mid-May 2026 and acknowledged the issue. The vehicle is currently at the dealership and available for inspection upon request. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Apr 14, 2026 · Transmission · NV

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. As coolant leaks from the cracked cylinder head, the turbocharger is deprived of its cooling supply, leading to excessive heat buildup and eventual cracking of the turbo housing. The turbo damage is a direct consequence of the cylinder head defect Mazda has already acknowledged. CSP11 covers the cylinder head but does not address consequential damage to the exhaust manifold and turbocharger caused by the same defect. I am requesting the federal safety agency investigate whether Mazda's remedy is sufficient and whether a formal recall is warranted given the risk of sudden engine failure at highway speeds.

Filed Feb 5, 2026 · Engine · IA

Here the facts, bought a car out of state (Illinois) from Iowa with 130,131 miles on Sept 12th 2025, Mazda CX9, the dealer did not disclose any problems with the car, after 3 months of ownership, the car overheats on highway whit family including a [XXX] infant, white smoke under the hood and exhaust pipe, towed home, radiator was replaced, few days after that a coolant leak, vehicle was sent to an authorized Mazda dealership for diagnose, the technician told us, according to Mazda procedures, a cod P111A, the vehicle's engine reached unsafe level of temperature and the whole engine needs to be replaced because a cracked head cylinder. This problem is well known by Mazda because they addressed on a TSB01-002/23 and CSP11 extended warranty, there is a flaw in the design of the engine near the cylinders manifold area, that cracks the engine and requires a full replacement of the engine. its just a flaw in the design of the engine. This issue can appear at any point threatening the life of the occupants of the vehicle INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)