Understanding the appropriate procedure and diagnosis codes for a particular study question is an important part of analyzing Medicare data. These codes are very specific and can change from year to year as new codes are added and others are discontinued.
There is no wear-out factor in the coil itself other than thermal cycling and the damage it may cause. Boots and wires do age, resulting in reduced insulation value over time. The key to correct ignition system diagnosis is to understand the details of how the system you are working on really functions. PAGE:
For vehicles with a coil on plug ignition system, a bad ignition coil would cause a misfire in one or more cylinders at once. The engine will still run, albeit quite powerless, and rough. Some coil on plug ignition coils actually control two cylinders with a waste spark system (as described above).