I have been made aware (by Dustin Palmer) that in 2008 Cummins used two O2 sensors on the ¾ ton 6.7L common rail diesel in Dodges. These have no urea system as that was introduced in 2011. They also have EGR, a TWC, and a diesel particulate trap. Yeah, according to the emission application that I looked up a TWC

Given that a diesel nearly always runs with plenty of extra O2 (I assume a HEGO will always show near zero volts) what could these sensors be doing? I assume that they are placed fore and aft of the TWC (efficiency test?) but don't know for sure.

Happy trails,

Rusty from Massachusetts