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:
A bad coil can cause the engine to idle and run rough. It might feel weak with a tendency to stall, and may start to backfire. When the coil fails completely it will cause a non-running condition, or in the case of a coil-over-plug application, a dead miss in that particular cylinder.