In this issue:
The on-board computer is capable of monitoring all of the sensors and actuators to determine whether they are working as intended. It can detect a malfunction or deterioration of the various sensors and actuators, usually well before the driver becomes aware of the problem.
All automobiles (including Subaru vehicles) are filled with dozens of multi-terminal connectors. They can be the source of intermittent and/or hard to diagnose electrical problems.
All late model Subaru four cylinder engines employ a “waste spark” ignition system. Testing methods for this type of coil are slightly different from what you might be accustomed to.