SCR Related: Idle Time=5 min. minimum and 10 min maximum. Hot shut downs have an effect on crystallization of the DEF injector. Once it gets crusted over it cannot spray DEF to reduce NOX. Hence alot of SCR related errors.
Soot//Ash Related: Komatsu machines have two different types of regen cycles-passive and manual stationary. These cycles vary due to boost leaks, engine oils, idle and cold run times, and quality of fuel burn't. Most operators have no idea or are not given proper time to perform a manual regen. When these procedures are ignored the soot filter in the muffler plugs and cause's a regen related errors in the machine.
Now factor in wiring, sensor issues, and a whole slew of other issues these are some of the problems in the industry, whether it be Cat, Komatsu, John Deere, Hyundai, Link Belt, Tak., Kubota, you name it.
Hope this helps explain a little about what I was referring to. Thx. guys