[JFP in PA]

Originally Posted by JRoser

The current fault codes from the durametric program are:

P1123 Oxygen Sensing Range 1 Cylinder (1-3)
P1125 Oxygen Sensing Range 1 Cylinder (4-6)

Thanks for guiding me JEP

Exactly what I thought, the codes indicate that both banks are running so rich that the DME cannot lean the engine out enough to get it into range. Most common fault: High fuel pressure (bad pressure regulator) or leaking injectors. As the codes are the same on both banks, I would start with a fuel pressure check.