I have heard a ton of people say Keep It Simple Stupid! That is very good advice that is so often not followed.
Complex machines with multiple sensors and controllers can overwhelm. I worked on a chipper recently that kept shutting down the feed rollers because of a drum speed warning.
A sensor monitors drum speed so that if the machine bogs down the feed disengages. The mechanic working on it went straight to the sensor and had no way to actually monitor the sensor output. He got bogged down in the complexity of the system and worked on it all day.
Turns out the sensor was doing its job and warning that the drum speed was too slow because the belt was slipping. After tightening the belt to specification the machine worked normally.
Mechanics have it harder today than ever before. We have to find out if there is a problem or if the monitoring system just thinks there is a problem.
Computers can often detect subtle incosistentcies before any noticeable symptoms appear. A code will often appear for an engine misfire long before you can hear the miss. If you start looking at the crank sensor assuming that it is giving you erroneous information you can derail your diagnosis. A compression test might seem to be a pain but until low compression is ruled out it could be th cause of the error.
We have all done it. Just add my reminder to all the other people that have told us to KEEP IT SIMPLE STUPID!