Is 2013 Isuzu Dmax EURO4 or EURO5

It could be either in 2013. There should be a emissions plate on it that has all the compliance information. Under the hood or on one of the door sills. We do not have them here so I couldn't say for sure where they attach the plate.

All Euro 5 vehicles have a DPF filter and soot accumulator, while Euro 4 engines usually do not have it. Of course, vehicle's plate reading is the best choice to find out. In worst case, you can try any menu as injector code programming to ECU memory has no relation to emission type and must be done by both menues, once you can communicate with system.