What 125 owners told NHTSA about the 2018 Mazda Cx-90 Phev

A coolant leak appeared around 62,000 miles. Car started overheating and come to find that I had no more coolant left in the reservoir. I filled it back up and drove it to the mechanic, after almost a week in the shop and have been quoted over $2k for the fix. There is a TSB out on this issue. It is a known issue apparently from a casting defect in the heads / block.

NHTSA ODI 11532749

A coolant leak appeared around 60,000 miles. I caught it in the right time as I had no more coolant left in the reservoir. I filled it back up and drove it to the Mazda dealership - I did not overheat at all so no warning lamps appeared. Upon taking it into the Mazda dealership, the engine was pulled and it was discovered that the cylinder head was cracked. This requires a new engine. There is a TSB out on this issue. It is a known issue apparently from a casting defect in the heads / block.

NHTSA ODI 11527344

coolant leaks at the cylinder head around the exhaust manifold , safety was compromised by car overheating in the middle of extremely high level traffic, problem confirmed by Mazda dealership, only inspected by dealership, there was no warning indicators from the vehicle. I could smell antifreeze the day before it overheated.

NHTSA ODI 11525408

A known faulty cylinder head in these cars is breaking. A simple search of the web shows numerous owners have had the same problem. Mazda dealers KNOW it is a problem. They have upgraded the part, but it comes at a cost of approximately $7800 to owners of said vehicles.

NHTSA ODI 11523363

Engine cylinder head cracks open due to bad design where turbo puts too much weight and vibration resukting in coolant leaking out of engine. Mazda has a bulletin out for this issue and I took it to a Mazda dealer for repair. They confirmed this was the issue.

NHTSA ODI 11522720

Bought car new in 2018. At 72,600 observed coolant leaking from backside of motor. Carried to Classic Mazda of Texarkana,TX for diagnostic test. Has a cracked cylinder head.Mazda refused to pay to fix or assume any responsibility for the design flaw. Turbo charger is too close to the cylinder head causing heat issues over time resulting in cracked head/coolant leak.

NHTSA ODI 11521555

Coolant leak at cylinder head. It is available for inspection. Driving on the highway and the car overheating light came on. Yes it has been reproduced and diagnosed as part of the TSB 01-013/21. No warnings, no notice of leaks before this happened. Noticed this in January - and thought it was just a one off and had the coolant topped off. Nothing happened until a month later that is when I took it to the mazda dealer. Safety issue as no one knows about it until their light comes on and they take it to the dealer to look at. Having this happen in the middle of nowhere on a highway with three small kids is a nightmare. This issue needs to be investigated. It is definitely a safety issue. It is shocking to know that Mazda has known about this for a couple years now based on the date of the TSB. A letter, at the very least, should have been sent out to all owners. Instead they let us all sit with a ticking time bomb that will be cost prohibitive to fix.

NHTSA ODI 11515906

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. I started researching to see if this was a defect and sure enough, Mazda has been aware of the defect with the cylinder head (TSB) not supporting the turbo of the engine causing it to crack and mix with the engine oil in various models for years, yet continue to sell cars with this known defect. I understand that it may not be life threatening yet! But it could have been should my engine had blown while I was on the freeway causing a horrific accident. How are they allowed to continue manufacturing and sell cars with a known issue for years and not even be reuqired to make a recall to have the part replaced with a stronger one? This is issue is happening to 100's of customers worldwide. This is something that should be investigated.

NHTSA ODI 11514604

Coolant leak into cylinder head, resulting in overheating and blown head gasket. Repair cost was $7k to resurface cylinder head and replace gasket. Repair did not fix issue, likely due to unseen cracks or warping to cylinder head. Will require rework, likely entire engine replacement, as the defect cannot be corrected.

NHTSA ODI 11511374

This weekend Mazda CX-9 started leaking coolant from the firewall side.

NHTSA ODI 11507063

Driving the car home from work, the engine temperature gauge started to go up high. I added coolant that same night. Went to the dealership for a check up. I was told the coolant was coming out from the back of the engine and will need to partial repair the engine. Only 75k miles in the engine and that was an estimate cause I could need a brand new engine. Now I’m stranded with out a car waiting for a response. MAZDA should do a recall regarding that issue cause I’ve seen a lot of CX9s have the same issue. THATS NOT GOOD FOR RELIABILITY.

NHTSA ODI 11501873

After owning this used vehicle for about 11 months, the engine temperature gauge indicated the car was running hot - about 240 degrees. After inspecting the vehicle at home, we added coolant to the system. This helped maintain engine temperature temporarily, but we noted over the next several weeks that the coolant was dropping rapidly. After inspection by a Mazda dealer, it was concluded that the cylinder head needed replacing.

NHTSA ODI 11499063

I have a 2018 Mazda CX-9 with about 66,000 miles. I noticed a coolant leak when my SUV sat in my driveway. It was there each night after driving the SUV. I took the vehicle to a Mazda dealer who stated that the coolant leak is from a cracked cylinder head. A cylinder head should not crack in 4 years and only 66,000 miles. This is a known Mazda issue for this year make and model.

NHTSA ODI 11490188

I noticed a smell of antifreeze. After taking it back to dealership, I find out it has a cracked head. It has never ran hot.

NHTSA ODI 11490050

The cylinder head failed causing a massive leak of engine coolant. This occurred initially at highway speeds which caused potential danger to myself and others around me as the car was required to pull over immediately. The problem was confirmed by the dealer and is known to the manufacturer as indicated by TSBs. The part was inspected and replaced by a new, redesigned part at the owner's expense.

NHTSA ODI 11489489

the cars engine makes loud rattling noise and slips gear. the vecicle jerks hard and feels as if transmission is slipping. car hesitates when i shift into gear, followed by a jerking and jolting into gear. my brakes are replaced frequently. mazda at 65643 miles on car found excess operating noise coming from engine coolant/water pump due to internal bearing failing. they replaced the water pump. software (pyd8-18881-f) replaced. the vehicle has 74000 miles and has same problem. when stopped at a traffic signal it lunges forward at times. and shifts slow to fast gears. this problem is not resolved. the first time it was allegidely fixed was 22Dec2021 it is now 05Oct 2022

NHTSA ODI 11488281

I purchased my 2018 Mazda CX-9 Grand Touring CPO with 39k miles and was sold the life time extended powertrain warranty through the dealership. The car now has 74k miles. While sitting idle at the school bus stop in my neighborhood waiting for my daughter the temperature gauge light comes on. I immediately drive home (exactly 0.3 miles) not going over 10mph back home, park call a tow truck company to tow it to the Priority Mazda dealership in Tysons Corner, VA from which I bought it. After a few days the mechanic calls and tells me there is a coolant leak and the repairs for the Cylinder Head should be covered under my lifetime extended warranty. A few days later I get a text message from the service rep that states. "Unfortunately, the extended warranty has denied coverage of the Cylinder Head, stating it to not be an internally lubricated issue....we need to fully inspect to determine what is needed (cylinder head or full engine due to overheating) Cost of teardown $1,432." After speaking to the service rep directly he then tells me the coverage was actually denied because Mazda put out a TSB on this known issue which voided my extended warranty on the cylinder head. This TSB bulletin no.01-007/22 was just issued 2 months before this happened. We should not be responsible for a known engine issue on Mazda's flagship car after purchasing an extended warranty for this very reason.

NHTSA ODI 11482726

While commuting home on 8/19/22 my CX-9 began overheating and coolant temp. warning light illuminated on dash. This was a dangerous situation as I had to stop in the middle of traffic for fear of ruining my car and risk getting rear-ended and also navigate to the shoulder of the road. Took the car to the dealership where they confirmed P111A engine overheated DTC and coolant leak. CX-9 has a cracked cylinder head, the exact problem outlined in Mazda TSB 01-013/21. This happened at 61,xxx miles...roughly 1,000 miles outside the powertrain warranty however it's highly likely this crack and leak developed well before the end of the powertrain warranty period.

NHTSA ODI 11481366

Car starting misfiring . I was told it appears to have a crack in the head gasket & would be best to repair the engine . This car has only 80k miles and should NOT be doing this at this stage!!!

NHTSA ODI 11471162

had loss of coolant mid to late January 2022, which lead to over heating notifications. Upon inspection at dealer (Pacifico Mazda Philadelphia PA), it was determined that i had a cracked cylinder head. Initially dealer said they were to replace just the cylinder head & after about 1 week they said that the engine would be replaced. Received car back 4/06/22

NHTSA ODI 11467194

When I shifted into reverse the back up camera wouldn’t come on and instead a screen that said check your surroundings stayed on the screen. I reset it using the 3 button reset method and it came back on. Drove it to the grocery store, and then it sat in my driveway for 3 hours. When I went to go back in to town, the car was completely dead. No power whatsoever. We tried jumper cables and those didn’t work. Finally tried a battery charger and after an hour of charging it finally came back on. A car this new shouldn’t be having these issues.

NHTSA ODI 11418943

HAPPENED TO ME TWO TIMES IN PAST THREE WEEKS, WHERE I AM COMING TO A STOP, OR HARDLY MOVING, AND CAR SUDDENLY ACCELERATES. HAD MY FOOT ON THE BRAKE AND THE CAR WAS STILL TRYING TO ACCELERATE. YESTERDAY, 4/24/21 IT TOOK ALL MY STRENGTH ON THE BRAKE TO KEEP THE CAR FROM PULLING INTO ONCOMING TRAFFIC. I HAVE BEEN DRIVING FOR 39 YEARS AND HAVE OWNED MANY CARS, AND SOMETHING LIKE THIS NEVER HAPPENED TO ME. I WILL BE BRING THE CAR DEALERSHIP TOMORROW, THE CAR HAS ONLY 10K MILES ON IT AS WE DON'T DO A LOT OF DRIVING WITH IT AS WE OWE TWO CARS. I DID NOT HAVE MY FOOT ON THE WRONG PEDAL, THIS IS VERY DANGEROUS AND IF THE DEALER DOES NOT FIND ANYTHING WITH THE CAR, I INTEND TO SELL IT, AS THIS IS PROBABLY ONE OF THE SCARIEST EXPERIENCE I HAD WITH A CAR. IT IS INTERMITTENT, SO I AM NOT SURE WHEN ITS GOING TO OCCUR, BUT TWICE IN THE LAST FEW WEEKS IS NOT COINCIDENCE ( IT ALSO HAPPENED TO MY WIFE A FEW MONTHS AGO, BUT WE THOUGHT IT COULD HAVE BEEN DUE TO SNOWY ROAD CONDITIONS). IN ONE CASE I WAS COMING UP TO A STOP SIGN, AND WAS BRAKING AND CAR WAS ACCELERATING AS I TRIED TO BREAK. I HAD TO PUT CAR IN NEUTRAL AND THE SHUT OFF CAR TO GET TO STOP. YESTERDAY, I WAS PULLING OUT OF A PARKING LOT, AND WAS WAITING FOR AN ON COMING CAR TO PASS ME BEFORE I COULD TURN ONTO ROAD, WHEN CAR WAS TRYING TO ACCELERATE, WHEN I HAD MY FOOT ON BRAKE, AND TOOK EVERYTHING TO KEEP THE CAR FROM ACCELERATING FORWARD INTO ON COMING CAR. ONCE CAR PASSED, I MADE TURN ONTO ROAD, AND ISSUE DID NOT REPEAT ON THE REMAINING MILE TO MY HOUSE. I WENT ONTO A MAZDA FORUM AND I SAW A FEW OTHERS WHO RAISED THE SAME CONCERN/ISSUE.

NHTSA ODI 11413732

I WAS WAITING IN A STATIONARY POSITION, AT A RED LIGHT, BEHIND SOME OTHER VEHICLES, WITH MY FOOT ON THE BRAKE PEDAL. ALL OF A SUDDEN, THE VEHICLE STARTED TO LURCH FORWARD AS IF SOMEONE HAD STEPPED HARD ON THE GAS PEDAL! I WAS STRUGGLING TO KEEP THE CAR STILL BY DEPRESSING THE BRAKE PEDAL HARDER, BUT IT WOULDN'T STOP THE CAR. I HAD TO PUT IT IN PARK AND TURN OFF THE ENGINE TO STOP THE FORWARD THRUST OF THE VEHICLE.

NHTSA ODI 11232824