Komatsu PC 360 lc troulbe code L03

So I have recently started back to work for a utilities contractor after some years off as a service tech. 2 things have came into play since I've started back, I've never serviced Komatsu equipment which is what brand this company has and all this DEF and emissions crap. In the past I've been able to use the internet as a platform to diagnose and fix alot of things that normally would be a dealer fix. So I've been searching on this Komatsu equipment and have not been able to find very much info at all. We have roughly 30 peices of machinery that is komatsu......and I have a PC360 LC thats's giving the code L03 in red on the display. In the past when the equipment was new I've been told that the dealer installed some sort of block off plate that has to do with the regeneration process. The machine has lost power and dies at random for no reason. What would you guys do? is there a computer program or something that is like a shop repair guide online we can purchase??? Since all their equipment besides a few is Komatsu where can I go for help. The local dealer isnt of much assistance so far. Thanks for any input in advance.

Komatsu PC 360 lc troulbe code L03