cadence was a part of the error code, but it did only do it with one magnet in the reduction gear and only the four easiest gears on my bike. Once I put the second magnet in, I had no problems with the speed Sensor, just a lower top speed.
There is always the mechanical option of speed derestricting. Planet3 offers a gear reduced magnet system that takes all of five minutes to install. I put it in my reign 1pro.
Works like a charm with two magnets and can hit speeds of 37km/h. You can use just one magnet and hit speeds around...