Hello. I am new here, I would like to know if anyone has had the problem with error messages? I have been going down our hill in LAKETAPPS parkway e auburn,wa.When i come up the hill it is about 291 feet going up a steep hill for about 20 mins,and the my bike stops with error message 13,and 15 at times trying to get up hill. I turn off display then turn it back on 15 sec it stops again with same error messages with the (!) flashing and error. This hill is very long and steep. It is very hard to push and hill so steep i cant go down it without having husband pick me up before coming home. Takes the fun out of riding it i cant rely on my bike alone. Any help would make the day worth riding it again. Thanks everyone.