there are minimum 3 area you always check in a ECU/PCM
most only check pending DTC which is for the A of ABC's in diagnostics.

if you looked at the HTTP in a previous response you will better understand the ED and welding curiosity.

Having formal training in welding is always a great thing to have.

 

Yes, I tend forget to check my "engine light" since it's been on since I bought this Mazda two years ago for minor evap codes but I do try to check them every 3-6 months when I do an oil change just to make sure no new codes have appeared. It's more I more worried about trying to get some suspension work done for safety inspection purposes, that was recommended back in January when I was able to get it to a professional shop to help diag the sounds it was making, since the parts and tools were located in the next town over and my inspection ran out 3-31-26 11:59pm and needed to a ride lined up to move it to where I'm living and move my backup daily to where I live since my GF doesn't have her drivers license yet.

But hopefully I can get repairs done soon to get it safety inspected again. Boosted my motivation to do repairs and back logged projects, on my days off, by sign it up for a car show in May.