Hwy guys...I'm chasing down a P219B code and looking to replace / substitute the upstream sensor. I already replaced the lower sensor (wonky waveform seen on my 'scope) without success. It was a bear, but got it done. The upper sensor looks even tougher, less room to swing a wrench. Anybody have any hints how to access it, from top or bottom?

2010 XK non-supercharged.