no "codes" for the headunit , its not that smart
swap the speaker from passenger side to drivers side using the same amps and wiring in the doors, that narrows down the speaker
if no then swap amps only and see if it carries to the other side, narrows down the amp.
if still no luck then try resetting the headunit. i think just disconnecting the neg. battery cable is the easiest way
i have whatever you need to fix it if you wanna troubleshoot or need other help lmk