I have had this issue recently as well (Nov 2022). I have a 2016 CX-9 with 95,000 miles. So unfortunately out of warranty. The dealer mentioned I will have to eat the cost and charged me $9,000 for replacing with a brand new engine. At the time it was urgent and I went ahead with it. Now I have a two-fold question:
1) I saw some posts here on folks being successful in getting Mazda to cover at least part of the cost. Can someone point me to a place where I can start with this? My email is
vijay.janki@gmail.com
2) I'm also having issues with the workmanship of the dealer. Shortly after replacing the engine, I had a gas leak from under the car (big safety issue) and it was the result of a deformed gasket of the incoming fuel line into the engine. The dealer fixed it at no charge of course. A week later the engine overheat sign came again on the dash with the warning of coolant required. Had the car towed to the dealer and they diagnosed that there was an air pocket in the coolant system that was pulling in a vacuum etc. They have fixed this as well. My question is whether the new engine is now affected because of these additional issues and additional warning of engine overheat (note that I immediately pulled over when the warning came and got the car towed)? How can I tell? While the new engine comes with a 3 year, 36,000 mile additional warranty, I don't want an engine that might have issues down the road.
Thanks for the help and suggestions