2000 7.3L throwing PO478 code

My ses light came on . I'm running a superchip on the lowest setting I think its 70hp for a year now . It has 134K miles on it and runs great. The PO478 code reads Exhaust Pres Ctrl Valve High Output. Its also throwing a PO470 code which reads Exhaust Back Pres Sens Circ Error. Has anybody dealt with this before?