MPE (Maintenance Plan Effectiveness) is a KPI to measure how effective maintenance plans are. It is the % of failure modes (including failure effects) that are 100% correctly described in a FMEA. This FMEA should always describe the ACTUAL failure behaviour. On this basis, the maintenance plans are drawn up and continuously optimised.
Maintenance and Reliability engineers use the MPE as a ToDo list. It is their job to manage failure behaviour and the MPE plays an important role here.