We've had that happen to us in our 2010 it happened right after we loaded a new tune into the computer, We believe it has somthing to do with your tuner/programmer , Just shut the truck off, And turn it back on it usually clears it up,
I had the same issue a couple of days ago but I know my tranny is on the way out. I've been having codes for a bit now and shifts like ****. Just saving money to repair. There has been few other people that this has happened too. Locking in forth gear is the tranny limp mod. From a few othe people having this issue, was traced to a bad ground on the PCM. Check the wiring harness and clean the grounds. That has fixed a few people. With it happening to you in a carwash sounds like that is the issue.