I have had a buzzing sound under the hood. Doing research, someone had an issue with the fuel rail vibrating/buzzing and it sounded exactly like the issue I am having. I brought my vehicle in to the dealership for an oil change and mentioned the issue. They claimed that they couldn't find an issue but torqued down the fuel rail. When I was driving home the sound was gone! But it has since returned. I reached out to Mazda USA and they have no records of any such issue existing and were no help.

This buzzing sound is noticeable at idle and the frequency goes up as the rpm goes up... as fuel is injected more rapidly. In the forum I found the resolution was to insulate the fuel rail where it is installed in order to reduce vibration. Simple enough, right!? It would be nice if the mechanics had documentation on how to fix the issue so that they know what to use to insulate and what to torque this to after the repair.

This is my second Mazda and I have noticed a pattern where if you have an issue the dealership will do their best to dance around the issue and "tighten" things as a bandage or they will replace a cheap part that they feel might be associated with it. I feel they do this in order to keep the cost of ownership down to help company metrics as doing research, a lower cost of ownership looks good right? Well, I am so tired of this practice. Just make note of it so you can address the issue and fix it for the future models!!!