I have a 2014 Hino 258 with 190,000 miles. It was running great and then all of the sudden the DPR bars went from 2 to all the way up and is in limp mode with the DTC P244B. Does anyone have an idea of what could be wrong?
The burner didn't light off, and the DPF is now clogged. Look in the engine customization menu to see how clogged. Somewhere around 8 g/L is safe to regen. Above that will melt the DPF. Look at DPF max outlet temp. If above 1300ish, remove DPF and pin test it. If It fails a pin test, replace it. If It passes the pin test but has higher than 8 g/l soot, have it baked.
The burner is fouled up. Do the P2030 checksheet, if you have access. If not, find the Burner maintenance thread and do that.
Finally, have the injectors evaluated. The burner is sensitive to high soot levels in the exhaust, and fuel injectors are a frequent culprit.