Hi, I think it is actually called the 'crankshaft position sensor' this video will help locate it.
https://www.google.com/url?q=https:/...HHZIMm2QmWbJ1U
It counts pulses generated by the teeth on the flywheel.
When mine failed on my old V70, the plastic mount had broken and the end actuall got trashed by the flywheel itself.
It is pretty easy to replace.
I also at another time had problems with bad connection into the sensor. You may have knocked this off.
A tell tale symptom besides the error code is that the tacho reads nothing when cranking. Understandable I guess.
Hope this helps
John l