Hey guys, i am getting p0442 and p0456. the dealer checked it out and said there wernet any leaks and im guessing i have a bad gas caps, i have tried 2 from autozone and they were aftermarket. should i try a oem from mazda or look into changing the filler neck? the gas cap cap i have on now, i can move it side to side kinda, so its loose is that a filler neck problem or i just got the wrong gas cap?

 

If you have a large evap leak then it would be a good idea to have a proper evap test run on the car. A smoke machine should be able to find the leak pretty quickly. Its pretty lackluster of the dealer not to run a smoke test or to properly run an evap test on the car and assume it's just a gas cap.

Oem parts are always your best bet over aftermarket. A gross evap leak can be a number of things, not just a faulty gas cap. You could have a purge valve or vent valve hanging wide open, you could have a bad fuel filler neck etc. If you are dead set on the issue being a gas cap then install an oem one, clear the codes, and drive the car until all readiness monitors are set and let us know if the gas cap fixed the issue.