When something 'breaks' on a car, it is fine one day, then - in a moment- something happens and you get a miss, a CEL, whatever.

There is almost certainly SOMETHING that occurred at that time... "I turned right". "I passed an AM/PM market"..."The cell phone JUST rang"...or "I filled up the tank one hour before (or 30 minutes or the day before)".

These are usually not causal events.

In a million plus miles of driving I have never had 'bad gas' that caused a CEL.