Abstract: An error injection tool for injecting errors into a computer channel wherein the error injection is under microcode control in the channel itself. Error injection may be random or precise, based upon inputted parameters. The injection can be either immediate or delayed, as desired. The resulting error injection may be layered such that an event may be set up to trigger a later error injection, with the layered error injection occurring in the true running environment of the channel. A time of day log may be constructed for timing the exact initiation and recovery time of an error.