Hey guys my check engine lights been on for about a month getting code 21 so I need to change my o2 sensor but have no idea where it is or how to do so. Looked online for videos and can only find ones on a Camry. Was just gona chop the cat off but I've been getting terrible gas mileage lately and I have a feeling it's cuz the check engine light. Any tips or tricks are very appreciated..

Also tried to unplug my battery and pull the ecu fuse I believe it was the e15 but the engine light is haunting me and won't go away