My 2016 700 starting blowing blueish gray smoke and smells like its running super rich I did find a bad exhaust leak at the flange before the O2 sensor and i just found out today i have two spark plugs dealer told me only one when i purchased smh thanks in advanced
An exhaust leak can cause the O2 to read a false lean condition and richen up the mixture. There can be negative pressure in the exhaust system (esp on a big single), and this will pull in oxygen rich outside air at any leak location.
IMO, the location of the O2 on the 700 is just begging for this to happen, since it sits right behind a joint that has been known to be leak prone.(Or as i really want to say, whoever put the O2 there was stupid...)
Probably a cost cutting measure, since the rear half of the pipe already had to be re-tooled for the cat anyway.