Fault-based unit replacement

A method and system are disclosed for determining the end of life condition for a replaceable unit, which may be associated with a multifunction device, and have a useful life expectancy based upon a number of operations. A counter associated with the multifunction device maintains a running count of operations for the unit. Once the number of performed operations of the replaceable unit reaches a given percentage of the expected life of that unit, an analysis is performed on a running history of the fault codes. Once the number of fault codes attributable to any given replaceable unit meets or exceeds a predetermined level, such as a percentage of the running history, a notification is generated indicating a need to replace the replaceable unit.