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

Cylinder head cracked at 100k. There is tsb knowing that this is a problem. It even stats that it happens during Manufacturing there was a defect. Coolant is leaking out the back side of the motor. Causing a over heating conditions stranding my family on the side of the highway.

NHTSA ODI 11586004

The 2018 Mazda CX-9 has been experiencing significant engine coolant leaks, which are suspected to stem from a manufacturing defect. The coolant leaks appear to be primarily caused by a casting defect in the engine block or cylinder head, exacerbated by the pressure and heat from the attached turbocharger. These defects lead to coolant escaping from areas that are typically obscured behind the exhaust manifold and turbocharger, making early detection difficult without detailed inspection.

NHTSA ODI 11585527

Car started leaking coolant, and running rough / stalling. Eventually overheated due to lack of coolant. Mazda dealer reports Cylinder Head crack as the root cause of the issue. Car has 106K miles - and seems to have the same problem as referenced in NHTSA 10232269 [XXX] ) Mazda has decided to decline to offer any financial assistance in the repair. Replacement cost for just the cylinder head (not a complete engine) was quoted by a Mazda dealership to be $6800 - $7200. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11583106

Engine coolant leaks at cylinder heads I started noticing the problem at around 50000 miles its a small coolant leak but car is almost 6 years old and now 54000 miles

NHTSA ODI 11576133

I recently bought a Mazda CX-9 and noticed that my vehicle was slightly overheating. The coolant level was very low. I took it back to the dealership I bought it from and they confirmed that there was a crack in the cylinder head and are working on the repair. After further research, I am seeing this is common with these models. Mazda is aware but not taking responsibility.

NHTSA ODI 11568859

Cracked Cylinder Head Verified by Mazda Dealer . Noted it seems to be a very common problem with Mazda cx9 2018 models and has Multiple TSB on issue so I kept very close eye on car and took it in as soon as I smelled burning smell suggesting a leak , before the car had the chance to overheat and put myself and kids in danger. My car is under 40k miles for a 2018 with consistent maintenance - this is known problem since 2021 and needs to result in a recall.

NHTSA ODI 11566536

Mazda has a known technical service bulletin [XXX] which has numerous engine cylinder heads which leaks coolant causing the engine to overheat without warning. On new cars. Mazda knows it’s an issue and has not pushed this information down to its consumers. [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11566091

Engine coolant leaking due to cracked cylinder head, found by Mazda dealership service inspection and diagnostics. Powertrain warranty only covers this until 80,000 miles, our vehicle is 116,000.

NHTSA ODI 11561290

At 102,000 miles I have a cracked cylinder head

NHTSA ODI 11560367

Cracked cylinder head resulting in no heat, leaking coolant and risk of overheating and fire. Crack on backside of cylinder head near exhaust manifold bolts. Weight of exhaust manifold is too much for the cylinder head and results in a Crack around the bolt. Cylinder head was casted too thin at the factory resulting in the head no being able to support the weight of the turbo and exhaust manifold. Mazda is not covering the defect under goodwill when customer is outside of warranty even though it effects every 2.5 turbo engine made between 2015 and 2020.

NHTSA ODI 11558860

The contact owns a 2018 Mazda CX-9. The contact stated that while the vehicle was parked, he observed condensation under the vehicle. The vehicle was towed to an independent mechanic where it was diagnosed that the engine needed to be replaced. The vehicle was repaired but the failure persisted. The contact stated that while the vehicle was parked, he observed condensation under the engine compartment and on the top of the engine. The vehicle was taken to an independent mechanic where it was diagnosed that there was a crack in the cylinder head and that the engine needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was 68,000.

NHTSA ODI 11558288

My 2018 Mazda CX-9 developed a rapid overheating issue which was determined to be caused by a cracked cylinder head. This was a known issue by Mazda as noted in a technical service bulletin (Mazda TSB 01-013/21). I've been told by Mazda corporate and the Mazda dealership where the car is currently parked that this bulletin means nothing and will they will not cover the cost of repair. My extended warranty is also telling me that they will not cover the cost of repair because they don't cover damage caused by overheating. Even though The leak caused the overheating in the first place.

NHTSA ODI 11554416

Coolant leak in the 3rd cylinder, causing the car to overheat and cracking cylinder head, making inoperable.

NHTSA ODI 11552567

We noticed a coolant leak and took vehicle in for service. Told that engine has a Coolant Leak at Cylinder Head [XXX] . 5 year old vehicle, 56k miles. No other warnings. All maintenance has been previously performed as required. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11551210

As I was driving 26 mile trip to work I noticed a red light illuminated on dash indicating the temp was about 240-260. I pulled into the parking lot immediately turned car off. After work (8 hour shift) drove home temp stayed at 200-210. The next morning I took it to the mechanic I’ve used for years. He did a visual detailed inspection finding that the water or antifreeze in the radiator was low. The antifreeze in the over flow tank was about an inch or so above the “L” line. He said there may have been an air pocket in it, a leak, water pump or thermostat going out. Watch the fluid levels daily, if the lower again take it to the dealership where I purchased it (4 months ago with 106K miles on it). I do have a 3 year or 30,000 mile warranty through the dealership. 4 days later I was very observant watching the temperature gauge. It went up to 240 briefly, so I got home and had my ex-husband check it. Both the radiator and the overflow tank were bone dry. Topped off radiator with antifreeze and the overflow tank to the “F” line. Car had cooled and right before topping fluid started. There is no noticeable sign of a leak (smell, white smoke from exhaust, visible puddles of anything on the motor or the ground where I’ve parked. Today is Thursday 10/12 and I can’t get an appointment with dealership until Tuesday. I’ve been reading a lot online about this being a very repetitive issue. In some cases new engine replacement required. Mazda is well aware of not a few but NUMEROUS issues and complaints, a recall is needed for this situation. Right is right and fair is fair!!

NHTSA ODI 11549523

Went in to the mechanic to get a regular oil change and noticed a liquid slushing sound after starting the car up. Was informed that there is a major coolant leak somewhere in the car. Took it to Mazda dealership right away who confirmed that it is a cracked cylinder head. I got lucky that the car did not overheat on the road and happened to catch it in the nick of time. No check engine lights or low coolant lights came on at all.

NHTSA ODI 11549216

Coolant leak not from radiator but from the engine

NHTSA ODI 11547442

Car started idling rough and losing power at 135000 miles. Then started to overheat. Mechanic noticed coolant was low and added some. Problem continued to get worse and now engine won’t turn over. Mechanic said it was a cracked head leaking coolant into engine and it’s a known problem with the CX-9.

NHTSA ODI 11546083

Just noticed coolant leak during oil change. Vehicle has 77,000 miles. Power train warranty is only to 60K. The vehicle is undriveable without major engine work or engine replacement.

NHTSA ODI 11545262

The cylinder head cracked and leaked engine coolant at 72K miles. This is a known design flaw IAW TSB 01-007/22. Vehicle overheated.

NHTSA ODI 11542796

Coolant leak from casting defect. Common issue.

NHTSA ODI 11541779

The vehicle started leaking coolant, I had it towed to dealer to prevent further damage. They said it has a cracked head, which is a known issue with the 2016-2019 Mazda's, and is acknowledged by Mazda to be their fault. They have posted on a service bulletin that it was caused by added stress during manufacturing. Like many others, they want me to pay over 8k dollars for the repair. This is ridiculous as Mazda has stated that it is their fault.

NHTSA ODI 11541472

I noticed my 2018 mazda cx9 Sweet smell coming out of the engine.. When we were driving, a memo came up on my car screen and says please turn off vehicle as soon as possible, overheating. I was Scared That my car could have stopped in the middle of the freeway with my kids in it. My current was low. My engine was really hot and so we took it in to Mazda dealer. They diagnosed my car, and they said it had a cracked cylinder head by the exhaust manifold and because of that, it overheated my engine. This is a manufacturer problem. And it could have harmed my family. Mazda now doesn't wants to help me fix my this car, even when admitting they are fully aware of it. This happening on a freeway would have caused a major accident. There are Technical service bulletin on this case but people are Still in danger.

NHTSA ODI 11541476

Driving on a major highway, when the engine overheating temperature light appeared on the instrument cluster. Seconds later it appeared and felt as if the engine would seize and come to an abrupt halt in the middle of a major highway. Thankfully I was able to quickly find a place with room to pull over, avoiding a potential collision. The engine coolant abruptly leaked/exited from the vehicle. I believe there is a service bulletin (No.- 01-002/23), but still no signs of a Recall being issued in reference to this safety concern.

NHTSA ODI 11539435

Started smelling coolant through AC and noticing that temp would momentarily spike to 240 before going back down to 200. My independent mechanic diagnosed it as a coolant leak in the cylinder head related to Mazda Tech Service Bulletin 01-002/23 (https://www.tsbsearch.com/Mazda/01-002-23). Took it to Mazda dealership, they confirmed a coolant leak and wish to replace the whole engine. Problem is that vehicle 1) has 105K miles and is not under warranty 2) Mazda engines are on back order and may not be available until November. I am going through an appeal process with Mazda right now to try to get some relief from a 9K repair bill. Disappointed that this known issue ( several threads in the Mazda forums ) is not getting the attention from Mazda that it deserves.

NHTSA ODI 11533550