What 99 owners told NHTSA about the 2016 Mazda CX-9

Cylinder head had a crack in it and had to be replaced.

NHTSA ODI 11570347

The car started to overheat so we added coolant and then the car started to stall had our mechanic look at it and he said the head gasket needs to be replaced. How is this not a recall

NHTSA ODI 11565213

The intercooler failed or failed cylinder head causing coolant leaking into the exhaust side and cause the engine to over heat.

NHTSA ODI 11564442

Engine is leaking coolant. Took the car to Horne Mazda of Avondale dealership for inspection, was told coolant is leaking from cylinder head. Was told the engine overheated and both cylinder head and cylinder block warped and will need to replace the engine. I feel my safety and others were at risk because the car could have lost power and stalled in the middle of roadway at any time due to there was no symptoms of my car engine overheated, car was running as normal, no check engine light, coolant temperature gauge did not show it was overheating, no sign of engine loosing power, no smoke from under the hood, no sweet smell or any indication engine is loosing coolant and overheating while driving. It appears to be a slow leak because coolant reservoir still have coolant above minimum level. First sign of coolant leak was notice during first week of October 2023 when small amount of green fluid was found on garage floor, took car to dealer on Oct.12.2023 for inspection. MazdaUSA refused to cover engine replacement under paid Mazda Extended Confidence warranty (MEC), blaming it's owners fault for operating car while engine overheated and refused to provide written copy of inspection details.

NHTSA ODI 11560271

The vehicle has tire pressure monitoring system malfunction warnings and parking brake malfunction warnings even after taking to dealership to be fixed. Was told it’s a known problem by Mazda, should be recalled, but there were not any current recalls for the issue.

NHTSA ODI 11559545

While driving, engine suddenly overheated due to coolant leak from cracked cylinder head. This was a known issue per the TSB 01-002/23. See attached. Vehicle only has 55k miles and has been maintained, only requiring oil change, topping off of fluids, and filter changes. Dealership has determined that it will require a completely new long block. Mazda USA is currently only willing to cover a small fraction of parts costs, requiring me to pay the remaining parts and all labor costs.

NHTSA ODI 11558846

Car started running rough and losing power intermittently. After arriving home and parking the car, a puddle of coolant started at the rear of the engine. Online research indicates this is a known issue for the 2016 CX-9. Head gasket failure causes coolant leak from back side of engine at the head gasket. Coolant is still leaking 24 hours later without the car being run.

NHTSA ODI 11553315

I have taken the Mazda CX9 since I bought it new to service at Mazda every 6 months or 5,000miles as suggested. Two years a new engine was required due to overheating and coolant problem which the service man noticed 5 months prior during service appointment but didn’t suggest doing anything. Now two years later new engine they installed overheated also.The Mazda has never been in a wreck of any sort. The Mazda has 86,000 miles on it only. How can a car have 2 engines fail in 7 years when it has been serviced there at the agency punctually as required?

NHTSA ODI 11552326

Coolant leak. Needs new motor to fix issue.

NHTSA ODI 11549198

The car has 75K miles on it and has always been maintained by either Mazda or independent garages. Engine overheating, took car to Mazda specialist and found the engine cylinder head is cracked. This is a known issue with this type of Mazda engine and Mazda has published a TSB which I attach. Car is unsafe to drive as coolant may leak completely at any stage and leave myself and family stranded. The cost of the fix exceeds $6,000!

NHTSA ODI 11548895

As I am accelerating to merge onto the highway from an on-ramp, while the gas pedal is depressed, I will get a series of sensor alerts simultaneously (city brake malfunction, park assist malfunction, lane assist malfunction, etc.) and my gas pedal becomes non-functional at 60-70mph. It is terrifying especially when there is other traffic around my vehicle. This exact issue has happened 6 times within the past 12-18 months at seemingly random intervals but always when I am accelerating onto the highway at 50-70mph. I typically pull off to the side of the highway and turn off the vehicle. After letting it sit off for ~30 seconds, I turn the vehicle back on and all of the sensor alerts have cleared and the vehicle functions properly including the gas pedal and I am able to rejoin the highway. I took the car to the Mazda dealership in my state of Vermont a few months ago to have them diagnose and address the problem. They had never heard of this issue and were unable to find the root cause or fix it. Please help, this is dangerous!

NHTSA ODI 11545342

I just had my engine replaced due to a cracked cylinder head that allowed coolant to leak into cylinder #3 & #2.

NHTSA ODI 11544838

Crack cylinder head

NHTSA ODI 11543910

Cylinder head crack/failure required the replacement of the entire engine on my 2016 Mazda cx9, the odometer was only at 85,000km. The crack Resulted in loss of coolant and overheating, the indicator on dash stating to pull over and shut the car off. This could have resulted in engine seizing if I was unable to safely pull over. This is a know issue by Mazda, the dealership has seen this issue before, there is lots of documentation online for this as well. There has since been updated parts to repair this issue, This should be a recall covered by Mazda. No car should require an entire engine replacement at 85,000km. This repair cost me $7700 out of pocket.

NHTSA ODI 11537889

First radiator blew (after noticing the temp gauge higher than normal and fan running a lot), and when replaced, the 2016 Mazda CX-9 continued to leak coolant. Took it to dealership to find out engine cylinder cracked and head gasket. A simple google search finds that so many Turbo Mazda’s between the years of 2016-20 experienced this design flaw as well. Mazda would not cover any of it since the car was out of warranty. It costed me over $7,000 to repair radiator and engine.

NHTSA ODI 11530871

My 2016 Mazda CX-9 2.5l Touring has approx 67,500 miles. I noticed the "sweet" smell of coolant after driving. The temp gauge was not showing signs of overheating. I checked under the hood and coolant level in radiator and reserve tank were normal. I also did not see any coolant leak/patches under the car. Few days later the car temperature gauge shot past the 1/2 mark. i stopped the care let it cool and checked under hood. radiator was empty but reservoir tank was still full. there were signs of coolant drips underneath car on the plastic cover below the area of the water pump (passenger front wheel side). waiting to have car assessed/fixed by mechanic.

NHTSA ODI 11528448

UKNOWN-Seat Heating system in my car gets too hot to the skin where it burns the skin if not turned off. I’m not able to use it often because even on low setting it gets extremely hot.

NHTSA ODI 11522786

While driving on the freeway in stop and go traffic the engine warning light came on. A few minutes later the data screen stated that I needed to pull over immediately as my engine was overheating. I was on a stretch of the 5 freeway north of Oceanside with no exits for several miles. I pulled over and when the light went off I got back on the freeway to try to make it to an exit. I repeated this process until I was able to exit and pulled in at the first mechanic I came to. The vehicle was losing power at that point. Pulling in and out of the traffic was hazardous to both me and the other drivers. When they inspected my car, they determined that the coolant had been leaking for a significant period of time as demonstrated by the worn spot on the pipe it had landed on. Further inspection revealed a blown head gasket. When a new head gasket was ordered from the local Mazda dealership, the mechanic was surprised to learn that Mazda had four of these parts in stock as most dealerships would have to order the part. The Mazda service department told him that they had four head gaskets in stock because this happens pretty often. My research on this site and on the Mazda forum indicates that this is a known defect to Mazda. This vehicle has just over 56,000 miles on it. It is regularly serviced. There was no warning light prior to this incident, in fact, the blue light indicating the engine was cool had regularly appeared whenever I started the vehicle. I have the replaced head gasket in my possession, should inspection of the part be necessary. I have reported this issue to Mazda but have been advised it is unlikely they will reimburse me.

NHTSA ODI 11521492

Head gasket blew in a 2016 Mazda CX9 while driving causing us to as safely as possible quickly get off the road from the middle lane of an interstate. This is from a known coolant leak in the cylinder head from service bulletin 01-013/21.

NHTSA ODI 11507815

I took my car into the dealership and was told that I had a cracked cylinder head and the car is leaking coolant near the rear of the engine. This could cause the engine to cease should coolant get into the engine. The dealer (North Park Mazda, San Antonio) has confirmed this as the issue. I have received a video of the inspection from the dealership explaining the issue. The vehicle displayed a warning that it was overheating which is what prompted me to bring the vehicle in for service.

NHTSA ODI 11503274

My engine head cracked whiling driving. sudden lost of complete power in houston texas at a 75mph speed. Was able to safely pull to the side. took it to the dealer where they confirmed it was a cracked engine head. Its a common issue with this model from 2016-2019 no warning light came on just lost 90% power. was able to restart and drive the 7 mins to the dealer.

NHTSA ODI 11499485

Car overheated. check front engine and could not see any visible leaks. check all around the engine and found coolant leaking from the back of the engine. confirm by dealer that is leaking at the cylinder head.

NHTSA ODI 11499498

At an intersection the engine stalled and car was extremely hard to restart (took several minutes). I later noticed oil and coolant dripping from the engine and coolant mist/vapor from the exhaust. Later I learned it was possibly related to Mazda's own TSB Bulletin No: 01-013/21 where a manufacturing defect caused coolant to enter the combustion chamber and hydro lock the engine (where I stalled and had hard time restarting). I had to have the car towed home. At home I noticed the passenger underside of the vehicle coated with oily/watery residue of possible oil or oil/coolant mix. Vehicle had 66K miles on and Mazda dealer refused to fix.

NHTSA ODI 11498923

I am being told by the dealership service center that there is a coolant leak from the engine. A previous coolant look due to a hose was repaired but this is a separate issue related to the TSB for coolant leak at the cylinder head Bulletin 01-007/22

NHTSA ODI 11498304

Cracked Cylinder Head due to Coolant Leak - SB 01-013/21. This is a known issue with Mazda, yet it has happened with the vehicle being serviced regularly. This is happens directly after the warranty period and it is not being covered.

NHTSA ODI 11493746