2004 Chevy 6.0L 2500HD P0300

Hello,
My pickup is throwing the infamous P0300 code and I'm not sure exactly what to do. It is an '04 2500HD with the 6.0L and a 5 speed manual tranny, and 92,000 miles on it. The truck seems to be running fine and when I took it to Auto Zone they gave me the code but couldn't give me the cylinders and told me to wait it out to see if it resets so I could save history on the truck in case it needs to go to a dealer. However, I don't want to cause more damage to the motor by driving If there is a serious problem. Unused fuel in the motor is not a good thing. I put new plugs and wires on a few months ago (85000 miles or so) and haven't had any trouble with it. I've looked online and I guess these trucks have this problem and it only gets worse with time. Any suggestions or comments would be appreciated.
Thanks,
Alex Weathers

There are alot of diffeent possibilities for that code on that truck. For starters is it still equipped with a distributor cap in 04 or was it switched to coil on plug by then? If it's still a distributor assy then I'd get a new cap from the dealer, not the zone or online and change that out, if it is COP and I think it is then I'd check for correct fuel pressure and volume and check for any vaccum leaks. As well does it feel sluggish like a restricted converter?

The truck is new enough that it doesn't have a cap, just the coils. It doesn't seem to run sluggish and it doesn't smell as though the converter is clogged. The right amount of fuel was something I had thought about as well as the sensor for the crankshaft. Also, I have heard that this code can be thrown if tires are spun a little on loose gravel or wet pavement and we have had a lot of rain recently.

That tire spin theory is a myth no offense! As for the smell the converter can be plugged and not smell different, often they smell different when something upstream of them isn't running right like an 02 sensor or a leaking fuel injector. The GM trucks have alot of early converter failures which can generate that DTC is the exhaust is restrictted and not generate the po420 dtc. Right now I'd be betting on fuel pressure or maybe a vaccum leak, what brand of spark plugs did you use? It come to think of it could cause the code if they're incorrect. If you an get a scanner that will log indvidual misfires and that will help narrow down which ones are missing as well as fuel trims, etc

Last night I went to move my truck and the check engine light just went off which is somewhat discouraging since now It isn't throwing the code. The plugs I used were not the exact ones that it called for because as a poor college student I couldn't afford $8 plugs, but i went with the next best thing and it has done fine thus far. I know a guy that works at a GM dealer and I was going to have him plug the truck in this afternoon so I could get the history on it I will let you know what he comes up with. I do know that these trucks are notorious for early intake gasket failures as well which is something else I had wondered about. I will check out the converter and see what I can find.

I took the truck in today to have the code read and was told that my fuel regulator is bad. I was told that I am running to much fuel into my cylinders which is causing the misfire. Unfortunately for my model of truck I have to get a whole new fuel pump assembly because it is all one unit. Any thoughts or second opinions on this diagnosis? I appreciate all of the help.

This is your friend from th GM dealer that confirmed this? It's quite possible! Like I've said excess or insufficent fuel pressure and volume will both generate that code. GM trucks have had fuel pump issues for a lot of years and are a very common failure. If they testted it correctly then it makes sense. I recommend only a fuel pump from the dealer. Alot of aftermarket brands don't last

Correct, that is what they said as well, that I should get the pump from the dealer. I will order the part and pull the bed off to replace it. Thanks again for all the help