Sudden gas mileage drop

[Spike555]

That is my understanding too, and that's why I did it. This ECU is 20+ year old technology, so a reboot after changing the air intake parameters was likely necessary.




There was no way to reset it with the cheapo OBDII reader I have unless there is a code. Then there is an option to "clear codes". Otherwise it just says "no codes found".

Also, if the vehicle is throwing a CEL, wouldn't it just come back on since the faulty part would still be faulty? That has been my experience.

Yes, unless you fix the cause of the check engine light resetting it will do nothing. The light will come back on after the ecu completes a drive cycle.
Thats why you cannot reset the check engine light by unhooking the battery.