P1000 Stuck in first gear

[Josh2021pioneer1000-5]

You've got a sensor in the diff that is unhappy or disconnected. The ECM is seeing that speed sensor and wont let it shift since it doesn't see speed.

Check if the gear indicator or CEL is blinking

The bike will run first and reverse and then shut off. Blinks 5x slow and 7x fast

 

[HondaTech]

The bike will run first and reverse and then shut off. Blinks 5x slow and 7x fast

I believe other users on here with code 57 have replaced or cleaned the shift motor and solved this issue.

Code 57 is related to a bad TR sensor, shift motor or incorrectly installed shift reduction gears. Since you haven't had those gears apart recently, I'd assume those are OK.