My wife owns a 2000 Miata. Recently the check engine light came on. She took it to O'Reilly's for the diagnosis. Three problem errors appeared: P0300 - Random misfire, P0455 - Evaporative Emission gross leak/no flow, P1345 - Cylinder discrimination signal from CMP sensor. The guy at O'Reilly's indicated none of the error messages were critical. Of course, that is just his opinion and is not coming from a mechanic, per se.

Any suggestions or feedback as to what to do next is appreciated.

P.S. About a year ago, I changed out the cam sensor and it fixed the problem we were having at the time.

 

Nothing critical..................................ummmmmmm mmmm yeah ok, a misfire is critical since it could destroy your cat-converter, an evap leak is critical cause it could leak fuel/fuel vapors out that may ignite. Try to get a new cam sensor again even if its a used junkyard one just to eliminate that variable as for the EVAP check your gas cap for a bad seal or if its just loose since its saying major leak. Misfire code could be related to cam sensor failure.

 

Thanks for the input. May not sleep too well tonight, though.

 

Misfire could be caused by a lot of different things:
plug, wire, rotor, coil pack, injector, vacuum leaks and a few more.

inspect, clean, test, re-use, and if needed replace.

If you can't sleep remind yourself: "it's just money!" ;-)