My 2013 F150 5.0 44k miles has had some check engine codes in the last 6 months. Ended up putting a used PCM in and seemed to cured issues.
Now I got a PO303 code that cyl 3 had too many misfires. Oreilly's read the code. Shortly thereafter I noticed the cel was not on and hasn't been on for a couple of days.
I thought cel latched on until reset, I didn't think Oreilly's reset codes. Not sure what to think.
Any thoughts
Thanks

 

Pull the plug and see what it looks like? Let’s start there.

 

You can get a basic code reader for less than $20 from several sources. I got one years ago and have used it on many years, makes, models of vehicles.

i get the code, then use google for meaning and possible caused for the specific vehicle.

before I do any repairs/parts swapping, I take a picture of the code displayed on the reader, reset the code and continue driving to see if the same code comes back, or a different code or just a glitch in the beginning.

the basic reader sure beats many trips to have the code read.