scr warmup

[JimT]

could check for a bad/faulty sensor or a damaged/broken wire for the temp sensors. It's possible there's an intermittent loss of signal. Also double check you ground connection/wires while your at it.

Not sure if any of those temps are calculated, but it does strike me odd that the DPF outlet temp is lower then the SCR inlet temp and the highest temp reading is from the SCR outlet? I'm not sure if it's even possible but, you didn't by any chance disconnect sensors/wires recently and somehow swap them around?

Also, have you inspected the {decomp tube} and can for DEF buildup or leaking? I don't know the design/layout of the exhaust on your truck but it's possible DEF could be building up and absorbing/deflecting heat from a sensor, if it actually is a sensor and not just a calculated value.

There's also the possibility that you have a blockage or leak in the DOC/DPF or exhaust system in general. That would throw the pressure readings off in turn messing up any values calculated from them.

The only other things I can think of is that either the turbo or EGR valve isn't functioning properly to keep the exhaust temps above the minimum threshold without kicking into warmup mode. But, then again, the entire point of warmup mode is to keep the temps up when the engine load isn't sufficient.

Anyway, I only have experience with my 2250 and it's long winding exhaust system underneath my truck. That was before it underwent corrective surgery, so the specifics of your system might be different from the mental model on which I'm basing my thoughts.