So I had my CEL come on, with my G63. Car was running completely normal. No hesitation, no rough idle, no poor MPGs, no issues driving at all. I got home and checked it with my scanner, P0305, “cylinder 5 misfire detected”. I cleared the code and went about my day. I do notice that everytime I start my car, the RPMs sit at 1200, even when the engines warm, then when I put it in gear the RPMs drop down to normal idling, like 600. If I turn off the car and turn it back on, the same RPM behavior?

A week later the light came on again, and the exact same code, again no driving issues. Everything I researched online recommends swapping the coil with another, to see if the code changes to that swapped cylinder, meaning a bad coil. I don’t think it’s bad coil, mainly because of no bad coil symptoms. Plus the spark plugs were changed about a year ago. Other possibles is a bad injector, or vacuum leak?

Before I take it into the dealership and pay an arm and leg for diagnostic, has anyone had the same issue? And what was the fix?

Any advices is greatly appreciated. Thanks!

 

Might let it run a bit longer before clearing codes. I had this problem and it ended up being an EVAP leak from on top of the gas tank.

 

Interesting. Like the seal for the fuel pump or gas cap?