Shift Range Inhibited??

My DIC on the dash has displayed this twice each time it did I was shifting from park (P) into reverse (R). What happens when the DIC says this?? (code set?)

Is this a result of a performance upgrade or does it just happen??

Sounds like it might be a faulty NSBU switch. Do a search on this site for NSBU and you will find it is a pretty common problem, nothing to worry about but you will need a new one.