2018 Mazda CX-9 Powertrain (other) Problems

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 ID

11731137

Incident

Apr 1, 2026

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 ID

11685844

Incident

Sep 8, 2025

coolant leaks at cylinder head , Mazda of America knows issues but not willing to recall , they hava a bulletin number 01-002/23 . pls help

NHTSA ID

11615751

Incident

Sep 20, 2024

Engine is leaking coolant apparently due to a cracked engine block caused by a manufacturing defect in the casting. Mazda has a Technical Service Bulletin, subject:Leaks at cylinder head and the number is 01-013/21. But they refuse to help cover their mistakes and now we owners are stuck with replacing an entire engine out of pocket. Shame on Mazda

NHTSA ID

11609045

Incident

Jul 29, 2024

My car started leaking coolant from cylinder, it is known issue for these models, unfortunately Mazda cooperation doesn’t cover the expenses, there is Service Bulletin about it, so basically so many car got affected or will affect from this problem. It is manufacturer fault, not about customer usage or mistake.

NHTSA ID

11603552

Incident

Jun 10, 2024

My vehicle had a coolant leak st the cylinder head around the exhaust manifold. The problem was confirmed by an independent service. No warning lamps, message or other symptoms of the problem prior to the failure did not appear. The problem was detected because coolant was dropping from the powertrain to the floor. When tha catalyst was removed it was found broken due to the high temperature but the car never display a high temperature warning lamp and the temperature display remains in normal position. The car could get on fire since no warnings or signal of high temperature was registered. After the situation occurred, I found a Technical Service Bulletin (No 01-01321) from Mazda North American Operations regarding this issue but since the problem occurred after the powertrain warranty the dealer did not accept to repair it. The probability that my car could get in fire was high since no warning lamps were display.

NHTSA ID

11594397

Incident

Feb 6, 2024

At 102,000 miles I have a cracked cylinder head

NHTSA ID

11560367

Incident

Dec 15, 2023

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 ID

11549216

Incident

Oct 9, 2023

The vehicle has a cracked cylinder head as a result of stress put on the block from a bad exhaust manifold design. This is a known issue to Mazda and service bulletin was sent out to all their dealerships in 2021. Mazda only offered to pay a very small portion of the repair and puts the rest of the cost on the customer. Luckily I caught the issue early but this could have been dangerous if the car overheated and the engine failed on the highway. There are countless other stories of consumers having the same issue with the CX-9 and CX-5 of the same year. Many resulting in engine failure.

NHTSA ID

11515492

Incident

Mar 30, 2023

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 ID

11514604

Incident

Mar 18, 2023

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 ID

11511374

Incident

Feb 8, 2023

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

NHTSA ID

11507063

Incident

Feb 11, 2023

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 ID

11488281

Incident

Oct 6, 2022