error codes p2195 p2196 p2197 p2198
 

I have 4 codes on my car that came up saying I need to replace both upstream o2 sensors I replaced both and still have the same codes. It's a stock 2006 mustang v6 4.0L. We checked the transmission harness wires. Checked o2 sensors. I don't know what else to do. Has anyone come across this issue before. Please help. Thank you