If there is a DTC (a "code"), then there very likely is something wrong with the RV that needs to be fixed. The DTC is to give you an understanding of which system is complaining that something isn't right. Diagnostics then needs to be applied to figure out root cause and fix. It's not just about clearing a code, unless you unplugged something while powered up that set the DTC.
Many DTCs will clear themselves once the root cause is removed.
Auto parts stores have scan tools for "OBDII", but not for most diesel powertrains (J1939).