2016 Mazda CX-9

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!

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.

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.

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.

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.

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.