So I'm fairly new to the infinity world. I've been going through threads but not sure where i should start. I have an '08 g37 coupe with a p0300 code on it (yeah it sucks cause it's a general code). I'm not sure where to start I have new cats on there new spark plugs. When I shut the car off it dies really rough. I'm not exactly sure where would be the best place to start.

 

I'm living the same hell as you my friend (my posts are in the "engines" subforum).
Dealership and I have been chasing this damn code for 2 months now. Have replaced a bunch of stuff and still no luck. Fortunately I'm still under warranty so no cost to me so far (aside of my time and patience).

 

p0300 is a random misfire code.

i got the same code when i changed to fast intentions HFC. what i did was clear the code. hasn't come back.

i would suggest clearing it and see if it comes back.

 

I tried getting rid of the code and it comes back a few days later

 

I would check there's no leaks where you installed the new cats. Also, check the O2 sensors are tight into the bungs.

My drivers o2 sensor was loose when I threw the code. My mechanic said this may have been the cause.

 

I'll give the O2 sensors a shot. That'd be nice if they were just not tight. Appreciate the help guys

 

Did this end up solving the issue? My car just started throwing this code. Trying to not sink a bunch of money into it if I don't have to.

 

Fyi my car was showing a misfire code. Replaced a lot of things. Ended up being the front left and right "o2" sensors. These are essentially afr sensors, and when they dont work right the car can lean out....

 

I had the same issue. Took it to the dealer updated the ecm and hasn't came back on (knock on wood)

 

https://www.myg37.com/forums/engine-...ill-there.html

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