Fault Code P0300

[z0lt3c]

Those just look like 80K mile spark plugs to me. Did you replace the plugs and the wires already??

Was their oil on the plugs or in the plug sockets? Are you loosing/consuming any oil between changes?

 

[605Jake123]

There wasn't any oil on them or is there any issues with the oil. There is still the rough idling issue after changing plugs and wires and every once in a while along with the random miss fire code I get the code bank 1 too lean. Which would make sense since half the plugs are white and half are black.

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[donut slayer]

Classic intake gasket problem. They have updated intake gaskets that fix the problem. Happens more often during cold weather.

 

[605Jake123]

That is what I have been told from some guys at work that have had this issue with gm trucks around the same year. I have an appointment for Monday to have it fixed and got a quote for the gasket installed for about $300 and if I want to have them put in two new knock sensors while they have the intake manifold off it will be an extra $200. I wouldn't mind trying to do it myself since I'm all about saving the money but I just don't have the time right now.

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[afpj]

I hope that extra 200 bucks includes changing the valley cover gasket while they're there. One less oil leak source to worry about in the future

 

[605Jake123]

Well had it looked at and all these issues were caused by a silly o2 sensor. I have never had an o2 sensor make it run so bad.

 

[afpj]

were there any other codes besides 0300? Wondering how they determined it was O2 sensor...Only way I can figure is by looking at the voltage wave forms while it's running. Which sensor, pre or post cat?

 

[bermudablueZ71]

those plugs definitely indicate an issue on one bank only. the 4 plugs being clean and a light brown would be burning perfectly, the other bank are dark and sooty appearing which screams too rich on that bank. Intake gaskets can do some weird drivability concerns, but they will usually affect all cylinders somewhat equally. being only on the one bank would have to be something that only controls or affects that bank. Glad you got it figured out, makes sense if the o2 sensor was always reading lean, (pre-cat) fuel trims would be high on the + side if you could see the data.

 

[Pachanga02]

Might need to change an 02 sensor as I've been having the same code, had my knock sensors replaced, and intake manifold gasket changed. Used FI cleaner and still get it. Which sensor was it?

 

[605Jake123]

I'm not really sure which one was changed and I can't seem to find my receipt right now. If it shows up I'll let you know

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