Have everything removed except the bottom 10mm bolt on the upper timing cover. It's rusted/pretty much stripped. I can't believe how tight this bolt is!

Any tips? The working space is really tight down there. Really need to change this sensor asap and get behind the wheel again...

Thanks.

 

Try a 10mm bolt remover socket.

 

Good penetrating oil (not WD-40) then let it sit overnight and use a cheater bar to loosen it.

 

None of the above.

You must use heat unless you plan on finding a way to drill out that tiny 6mm thread and put it back in the exact spot.
Use a common handheld propane torch for pipe soldering to heat the bolt. YES< the sensor will melt but it's bad anyway. Use a water spray bottle to keep anything close that burns cool. Heat the bolt until it glows at least once and let it cool off a minute.

Put a six point socket on it and work it back and forth in very small increments until it will come loose. You do not want to break that screw. Take your time. Good luck.