Why am I having transmission fluid leak after upstream 02 sensor change and bad downstream?Cooling line driver side for transmission

Hello, Dave here, contributing to RepairPal and providing expert advice since 2010. I appreciate that you're having difficulties with your vehicle. I'm hearing a lot of symptoms, but no testing or reasonable physical inspection determining root causes of the issues. If the transmission fluid is leaking, it must be narrowed down to the source of the leak. This can be a line, a cooler or the transmission itself. As far as diagnostic trouble codes (DTC) being set for engine performance and emissions system issues - testing must be performed to find out why the codes are being set. Are they rich, lean or circuit concern codes with the sensor readings? Codes do not condemn the component directly; they instead give clues which help with drilling down to the source of what is happening causing the problem. Sounds like a few different things going on; you'll want to take each thing individually and get to the bottom of what will be multiple issues. Reach out to a shop near you for help -- https://repairpal.com/auto-repair-near-me Click the link or call us at 877-913-1554. We'll gladly find you a certified RepairPal shop in your area.