CM871 High DOC temp during regen

[JimT]

If the above reset doesn't change anything then maybe you should look in to electrical causes. Check all wires, look for anything that could be damaged. Check ECM. I think the recommended "test" is to warm the engine up and tap the ECM with a hammer?

Also, have you been monitoring the actual sensor readings in Insite with Data Monitor or tried any of the sensor diagnostic tests? These too could help you identify possible causes. Could be a short somewhere, a bad ground or even a bad sensor or bad electrical connection at a plug. Your symptoms are a bit odd. But I keep going back to the last repair before it all started, the doser valve. Not sure what else might have been involved, but it sounds like some kind of wiring or electrical issue. Maybe the original doser issue was just a symptom of something else? IDK, just thinking out loud, maybe it sparks an idea...