I seem to have a weird problem with my Garmin 800.

Simply, it’s massively under-reading on distance compared to other Garmin GPS units in the group. Like 25-30%. Oddly the breadcrumb trail is fine, shows accurately on the map where we have been, it’s just the indicated distance that is way out. I’ve also noticed that it suddenly has got very unreliable on height as well, going from being pretty much spot on to often hundreds of metres out.

The lock is good (3-5 m), but even when it’s obvious that you’ve done, for example, 1 km on the map, it will show anything from 200 – 700 m. This is in steep terrain, but even so…

Anyone have any ideas?