All you need to know about the N62 engine:
https://www.internetsomething.com/lp...2%20Engine.pdf
What other codes are present? A bad misfire will also show up as bad O2 readings. Common ones are P0420 and P0430.
A normal compression tool will work. Inspect the coil electrical connection. What year is it? Did the N62 go through coil lock down connections too?