Code 21a

[Muskie1]

 I live near some historic areas, so last night I decided to take a ride up to Fairlane,  Henry Ford old mansion.  I come out code 21a maybe,  bike would not power up, no glasses , pulled the battery,  ok now. . What is the 21 code if anyone knows.

[Si1Dia]

Here is Rad's guide to error 21:

https://radpowerbikes.zendesk.com/hc/en-us/articles/360015396794-Error-21-Troubleshooting-Guide