My car been having this 02 sensor code /service engine soon code for awhile now like a month and I’ve replaced the 02 sensors twice and I’ve took it to two different car shops, fire stone says it’s my catalytic converter without doing any work they look at it for like 10 mins and was like it’s this, although they is rusted cause my car is a Infiniti g35x sedan 2007 so not the new stuff but I also took it to meineke and they said it’s not my cata and that my 02 sensors had a freeze in the system or something like that and that they found another code which is p1815 for my transmission sensor switch, at this point I’m not sure what to do, before I got my 02 sensors fixed I had my y pipe switched out cause it was pretty loud and then it got quiet and now it’s back a lil loud which makes me think can it just be a leak somewhere?