Originally Posted by
DrIsotope
From the P2M FAQ page: [...] You can also update the zero offset manually through a compatible head unit.
Yeah, P2M is a pretty good power meter, but they like to claim that it's impossible for end-users to check their accuracy and precision without special tools and procedures that only they know about
: "Just trust us." Stages used to make the same claim.
The manual setting of zero-offset is what the Garmin head units do when you "calibrate" a power meter.