CAT 277d DPF code

[Nige]

I also found the pictured sensor unplugged. I assume that is an air intake temperature sensor and likely doesn't have much impact on this issue as there are no related codes.

It's actually an inlet pressure switch that trips an alarm for a plugged air filter indication once the deltaP exceeds a certain level. You should be able to confirm by looking for "430" stamped on the outside of the insulation on the Blue wire.

 

[Nige]

If cleaning is successful i will plan to reset the soot levels.

IIRC it requires a dealer version of ET to do the soot reset, maybe even requires factory passwords as well if I’m not mistaken. The Customer version of ET does not have that facility.