I plug in a code reader and clear the code until the next time it happens in ~6 weeks.

I've read changing the serpentine belt is a solution, but have not done it yet.

 

Hey Simon, thank you! Even I did get it cleared, but it comes up and goes on its own! Super annoying though as I can't use DNA and remote start though!
Gotta check my serpentine belt though as you suggested!

Thanks again!

 

Evidently, your engine is perfectly fine and that generic misfire error code is because of something weird else. Did you check your battery health?. Low and/or bad battery in these cars make things act up. Even if the battery is good enough to start the engine all the time with no issues, it could be actually bad and causing CELs for different not related things.

 

If the P0300 code is the only code you have, you are going to want to have the dealership monitor misfires on a cold start and see if a certain cylinder is misfiring more than others, if so that would be indicative of a problem in a specific cylinder. If not, you may want to have them perform a phonic wheel and VCM relearn(crankshaft position and Multiair). If the crank position learn is off slightly, it will cause erroneous misfire detection, especially on cold start. Also, as an Alfa tech, I have never actually seen a stretched serpentine belt cause a misfire. There is actually a small arrow indicator on the top of the tensioner that will tell you if the belt is in specification or stretched.... and I've never seen one stretch out of range.

 

Is it possible that an engine works perfectly fine all day long, in any conditions, RPMs and driving modes but, it has a misfire issue in certain cylinder (or all cylinders) in cold starts? or it has the crank position learn off slightly and cause erroneous misfire detection?

 

Man, just parking on a "steep"ish angle will cause this nonsense. I know all the signs now, start car, within a minute or so the auto start/stop is disabled, car drives just fine, D mode, whatever. If you turn it off and back on before it "goes to sleep" (for lack of a better term), the CEL comes on. Turn it off and leave it and come back after it's "gone to sleep" and everything is fine.