KCORNISH,
Most of the Komatsu fault codes are 6 digits in length. There are general action codes, E01,E02,E03 that are three digits in length but general action codes just give operator directions as to the severity of fault and whether or not the operator needs to shut the machine down or not.
On the dash2 HM300's you have to toggle the > switch to see actual fault code which is different from the general action code.