2018 Mazda CX-9 problems

ENGINE

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.

NHTSA complaint #11755628 — an unverified report by a vehicle owner.

ENGINE

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.

NHTSA complaint #11750583 — an unverified report by a vehicle owner.

SEATS

My passenger heated seats malfunction while I was driving. As I was driving on the highway I smelled something burning. I didn't know where the smell was coming from it was strong . Then while I'm driving on the highway my seat started to smoke a lot I got scared and pulled on side of the road. I realized my seat was the issue turned off the heated seats on the control. Step out the vehicle on side the highway I was nervous and scared standing outside my vehicle. The smoke eventually died down and cleared out. I never turned it back on and put a small piece of tape over the hole it burned through my seat.

NHTSA complaint #11742848 — an unverified report by a vehicle owner.

ENGINE

My wife was driving the vehicle when the emergency lights started going off. She had to pull over because the car wouldn't run and said it was overheated. All the maintenance has been done to the car. We took it to the dealership and they said it is a cracked head and it is a known issue. They even issued a extended warranty for it. It is TSB 01-002/23. There should be a recall on this not just a partial credit.

NHTSA complaint #11742255 — an unverified report by a vehicle owner.

POWER TRAIN

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 NHTSA investigate whether Mazda's remedy is sufficient and whether a formal recall is warranted given the risk of sudden engine failure at highway speeds.

NHTSA complaint #11731137 — an unverified report by a vehicle owner.

ELECTRICAL SYSTEM

The liftgate (trunk) opens sporadically. The system keeps trying to open the truck and it's causing a parasitic drain on my battery. I was stranded 2 hours from my home due to this. My trunk would sporadically beep three times, that is the only warning I received. There are safety recalls for other year of Mazda cx-9 but not my specific even though I am having the same issue.

NHTSA complaint #11725165 — an unverified report by a vehicle owner.

ENGINE

My 2018 Mazda CX-9 experienced catastrophic engine damage after a radiator failure allowed coolant to enter the engine. The vehicle provided no dashboard warning, overheating alert, or coolant warning before the failure occurred. Modern vehicles are designed to alert drivers to overheating or cooling system failures. The lack of warning prevented me from addressing the issue and resulted in catastrophic engine damage. I believe this represents a potential safety defect in the vehicle’s cooling system monitoring and warning system.

NHTSA complaint #11723876 — an unverified report by a vehicle owner.

SERVICE BRAKES

My 2018 Mazda CX-9 experienced catastrophic engine damage after a radiator failure allowed coolant to enter the engine. The vehicle provided no dashboard warning, overheating alert, or coolant warning before the failure occurred. Modern vehicles are designed to alert drivers to overheating or cooling system failures. The lack of warning prevented me from addressing the issue and resulted in catastrophic engine damage. I believe this represents a potential safety defect in the vehicle’s cooling system monitoring and warning system.

NHTSA complaint #11723876 — an unverified report by a vehicle owner.

SEATS

The adjustable rails holding the rear left seat in place no longer latch. It is available for inspection. This is the most common place for a car seat in this car. In the event of a crash the seat would slide forward. The seat belt attaches to the seat so there would be little restraint on the rear passenger. The mechanic who attempted a repair stated Mazda does not sell this part, only sells a replacement for the entire seat, about $5000. There were no symptoms, when adjusting the seat the rail just stopped holding the seat firmly in place when the adjusting bar was released.

NHTSA complaint #11719629 — an unverified report by a vehicle owner.

SEATS:MID/REAR ASSEMBLY

The adjustable rails holding the rear left seat in place no longer latch. It is available for inspection. This is the most common place for a car seat in this car. In the event of a crash the seat would slide forward. The seat belt attaches to the seat so there would be little restraint on the rear passenger. The mechanic who attempted a repair stated Mazda does not sell this part, only sells a replacement for the entire seat, about $5000. There were no symptoms, when adjusting the seat the rail just stopped holding the seat firmly in place when the adjusting bar was released.

NHTSA complaint #11719629 — an unverified report by a vehicle owner.

ENGINE

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)

NHTSA complaint #11716057 — an unverified report by a vehicle owner.

VISIBILITY/WIPER

Passenger side sun visor will not stay in place. Cannot lock it in up position, which means it droops. Causing sight of vision impairment.

NHTSA complaint #11694595 — an unverified report by a vehicle owner.

ELECTRICAL SYSTEM

[XXX] 2018 MAZDA CX-9 GRAND TOURING 89014 MILES Date: 9/11/2025 To: Mazda North American Operations Attn: Customer Experience Center 7755 Irvine Center Drive Irvine, CA 92618 USA Subject: Formal Complaint Regarding Safety and Technical Issue – 2018 Mazda CX-9 Dear Mazda Customer Experience Team, I am writing to formally lodge a complaint regarding a serious safety and technical issue I have experienced with my 2018 Mazda CX-9. After a recent inspection conducted by Mazda Koch 33, it was brought to my attention that the engine wiring harness is defective and may potentially cause a fire or result in burns, posing a severe safety risk to me, my passengers, and others on the road. This issue is deeply concerning and unacceptable, especially considering Mazda’s reputation for reliability and safety. A fault in the engine wiring harness, particularly one that has the potential to ignite or burn, should be treated with the utmost urgency. It is troubling that such a critical component could present such danger. My vehicle has been serviced and maintained regularly, and I was not made aware of any recall or technical service bulletin that addressed this defect until the inspection. Given the nature of the defect, I believe this may be a manufacturer defect, and I request that Mazda: Immediately investigate and confirm whether this issue falls under an existing recall or known defect. Take full responsibility for replacing or repairing the affected wiring harness at no cost to me. Provide assurances in writing that my vehicle is safe to operate. Offer compensation or a loaner vehicle if the repair process renders my vehicle unusable for any period of time. Please consider this a formal request for immediate corrective action. I expect a prompt response within 10 business days of the date of this letter. If I do not receive a satisfactory resolution, I will be compelled to escalate this matter further through consumer protection agencies, such as the INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATI

NHTSA complaint #11686751 — an unverified report by a vehicle owner.

BACK OVER PREVENTION: WARNINGS

[XXX] 2018 MAZDA CX-9 GRAND TOURING 89014 MILES Date: 9/11/2025 To: Mazda North American Operations Attn: Customer Experience Center 7755 Irvine Center Drive Irvine, CA 92618 USA Subject: Formal Complaint Regarding Safety and Technical Issue – 2018 Mazda CX-9 Dear Mazda Customer Experience Team, I am writing to formally lodge a complaint regarding a serious safety and technical issue I have experienced with my 2018 Mazda CX-9. After a recent inspection conducted by Mazda Koch 33, it was brought to my attention that the engine wiring harness is defective and may potentially cause a fire or result in burns, posing a severe safety risk to me, my passengers, and others on the road. This issue is deeply concerning and unacceptable, especially considering Mazda’s reputation for reliability and safety. A fault in the engine wiring harness, particularly one that has the potential to ignite or burn, should be treated with the utmost urgency. It is troubling that such a critical component could present such danger. My vehicle has been serviced and maintained regularly, and I was not made aware of any recall or technical service bulletin that addressed this defect until the inspection. Given the nature of the defect, I believe this may be a manufacturer defect, and I request that Mazda: Immediately investigate and confirm whether this issue falls under an existing recall or known defect. Take full responsibility for replacing or repairing the affected wiring harness at no cost to me. Provide assurances in writing that my vehicle is safe to operate. Offer compensation or a loaner vehicle if the repair process renders my vehicle unusable for any period of time. Please consider this a formal request for immediate corrective action. I expect a prompt response within 10 business days of the date of this letter. If I do not receive a satisfactory resolution, I will be compelled to escalate this matter further through consumer protection agencies, such as the INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATI

NHTSA complaint #11686751 — an unverified report by a vehicle owner.

LANE DEPARTURE: WARNING

[XXX] 2018 MAZDA CX-9 GRAND TOURING 89014 MILES Date: 9/11/2025 To: Mazda North American Operations Attn: Customer Experience Center 7755 Irvine Center Drive Irvine, CA 92618 USA Subject: Formal Complaint Regarding Safety and Technical Issue – 2018 Mazda CX-9 Dear Mazda Customer Experience Team, I am writing to formally lodge a complaint regarding a serious safety and technical issue I have experienced with my 2018 Mazda CX-9. After a recent inspection conducted by Mazda Koch 33, it was brought to my attention that the engine wiring harness is defective and may potentially cause a fire or result in burns, posing a severe safety risk to me, my passengers, and others on the road. This issue is deeply concerning and unacceptable, especially considering Mazda’s reputation for reliability and safety. A fault in the engine wiring harness, particularly one that has the potential to ignite or burn, should be treated with the utmost urgency. It is troubling that such a critical component could present such danger. My vehicle has been serviced and maintained regularly, and I was not made aware of any recall or technical service bulletin that addressed this defect until the inspection. Given the nature of the defect, I believe this may be a manufacturer defect, and I request that Mazda: Immediately investigate and confirm whether this issue falls under an existing recall or known defect. Take full responsibility for replacing or repairing the affected wiring harness at no cost to me. Provide assurances in writing that my vehicle is safe to operate. Offer compensation or a loaner vehicle if the repair process renders my vehicle unusable for any period of time. Please consider this a formal request for immediate corrective action. I expect a prompt response within 10 business days of the date of this letter. If I do not receive a satisfactory resolution, I will be compelled to escalate this matter further through consumer protection agencies, such as the INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATI

NHTSA complaint #11686751 — an unverified report by a vehicle owner.

POWER TRAIN

my 2018 MAZDA CX-9 safety issue SCBS / SBS, LAS / LDWS, MASTER AND/OR HBC WARNING LIGHTS Forward sensing camera (FSC) stops functioning cause my car run rough even depress accelration and those light came on dashbaord -Forworad smart city brake support malfunction -smart brake system -front camera sensor malfunction

NHTSA complaint #11685844 — an unverified report by a vehicle owner.

ELECTRICAL SYSTEM

my 2018 MAZDA CX-9 safety issue SCBS / SBS, LAS / LDWS, MASTER AND/OR HBC WARNING LIGHTS Forward sensing camera (FSC) stops functioning cause my car run rough even depress accelration and those light came on dashbaord -Forworad smart city brake support malfunction -smart brake system -front camera sensor malfunction

NHTSA complaint #11685844 — an unverified report by a vehicle owner.

SERVICE BRAKES

my 2018 MAZDA CX-9 safety issue SCBS / SBS, LAS / LDWS, MASTER AND/OR HBC WARNING LIGHTS Forward sensing camera (FSC) stops functioning cause my car run rough even depress accelration and those light came on dashbaord -Forworad smart city brake support malfunction -smart brake system -front camera sensor malfunction

NHTSA complaint #11685844 — an unverified report by a vehicle owner.

ELECTRICAL SYSTEM

I am submitting this recall request because my vehicle has experienced repeated incidents of a serious safety issue. While driving—most often on the highway—a warning appears that says “Smart System Brake Malfunction.” Immediately after, the car begins braking on its own without driver input. This has happened multiple times and, based on online reports, it appears to be affecting many Mazda vehicles across different models and years. Each time, I have been forced to pull over, turn off the car, and restart it to temporarily resolve the issue. This is extremely dangerous, especially at highway speeds, as it creates a high risk of rear-end collisions and sudden loss of vehicle control. When reported to Mazda, the concern was dismissed as a “sensor issue,” but the repeated nature and widespread reports suggest a potential systemic defect that requires urgent investigation and recall.

NHTSA complaint #11682407 — an unverified report by a vehicle owner.

SERVICE BRAKES

I am submitting this recall request because my vehicle has experienced repeated incidents of a serious safety issue. While driving—most often on the highway—a warning appears that says “Smart System Brake Malfunction.” Immediately after, the car begins braking on its own without driver input. This has happened multiple times and, based on online reports, it appears to be affecting many Mazda vehicles across different models and years. Each time, I have been forced to pull over, turn off the car, and restart it to temporarily resolve the issue. This is extremely dangerous, especially at highway speeds, as it creates a high risk of rear-end collisions and sudden loss of vehicle control. When reported to Mazda, the concern was dismissed as a “sensor issue,” but the repeated nature and widespread reports suggest a potential systemic defect that requires urgent investigation and recall.

NHTSA complaint #11682407 — an unverified report by a vehicle owner.

FORWARD COLLISION AVOIDANCE: AUTOMATIC EMERGENCY BRAKING

I am submitting this recall request because my vehicle has experienced repeated incidents of a serious safety issue. While driving—most often on the highway—a warning appears that says “Smart System Brake Malfunction.” Immediately after, the car begins braking on its own without driver input. This has happened multiple times and, based on online reports, it appears to be affecting many Mazda vehicles across different models and years. Each time, I have been forced to pull over, turn off the car, and restart it to temporarily resolve the issue. This is extremely dangerous, especially at highway speeds, as it creates a high risk of rear-end collisions and sudden loss of vehicle control. When reported to Mazda, the concern was dismissed as a “sensor issue,” but the repeated nature and widespread reports suggest a potential systemic defect that requires urgent investigation and recall.

NHTSA complaint #11682407 — an unverified report by a vehicle owner.

ENGINE

Cracked cylinder head/leaking coolant.

NHTSA complaint #11681066 — an unverified report by a vehicle owner.

ENGINE

. In January 2024, I purchased a used 2018 Mazda CX-9. The vehicle ran well until [XXX], when I discovered an engine coolant leak. My mechanic diagnosed it as a known defect involving the cylinder head. My husband contacted Mazda Customer Service (CS), and they advised us to get an official diagnosis from a Mazda dealer. We brought the car to Orland Park Mazda, where a diagnostic confirmed the defect (report attached). We later received an email from Mazda CS saying that since our car was at the dealership, Mazda would take the lead in submitting the goodwill repair claim (email attached). When we followed up with Orland Park Mazda, they informed us that no one from Mazda CS had contacted them to authorize the repair. We relayed this to Mazda CS and gave them the direct number of our service advisor, Adrian. Mazda CS said they would follow up and get back to us within 48–72 hours. On a follow-up call, I spoke with Nancy at Mazda CS, who again told me that our case manager Cindy would contact us within 48–72 hours. Instead, we received an email denying the repair, stating the vehicle exceeded the 120,000-mile limit for the extended warranty (our vehicle has 133,500 miles). While our car is outside the warranty period, this is a textbook case of a well-documented defect covered under TSBs for the 2018 CX-9. Mazda has previously approved goodwill engine replacements for other customers well beyond this mileage. We are seeking fairness and consistency in handling known product defects. Our request is that Mazda approve the engine repair under goodwill coverage as they have in many similar cases. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA complaint #11674928 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

Infotainment screen (LCD) of Mazda CX-9 2018 has developed what looks like discoloration/scratching/frost in corner of screen about 2 years ago and it is continuing to spread over last 6 months. This screen is used for hands-free bluetooth/calling (which is now the law in Iowa) and the back-up camera which allows for safe backing. If screen is unreadable, these safety functions cannot be performed properly. I take my car into Mazda dealership for maintenance/oil changes and it has never been addressed as an issue, but I'm concerned.

NHTSA complaint #11673548 — an unverified report by a vehicle owner.