vht

ms




Hope this is the right place, I have a 2005 chevy 2500 HD with the 6.0. I get PO300 code constantly, clear it and when you get to 50 or 55 MPH the light starts flashing. Also I get cat codes and knock sensor codes at random, plus it'll go in limp mode and won't accelerate
unless you pull off and shut it off for 3 minutes or so. It's done that 4 times lately but it may go 2 mths before it does it again. It runs great, no misfire that I've ever felt. It has new knock sensors, intake gaskets and a GM crank sensor. Anyone have any ideas? I would really like to figure out this 300 code. Also it uses some oil, did the 05 get the screwed up valve cover that pulls oil through the pcv? I put a new pcv in it.

Tommy42088

Did you use gm knock sensors? Also start with the basics. Spark plugs, coils, injectors, fuel pressure,

LS1Formulation

iTrader: (13)

I have a 2006 LQ4 in a 2500 HD Silverado. Was getting the P0300 code all the time at highway speeds. Turns out I needed to do a crankshaft variation learn. I did that and haven't had a problem since. I will say, I had to to knock sensors on mine and aftermarket ones SUCK. I had some GM ones on my blown up LS1, so I installed those with zero issues since. Get a good scanner and do a crankshaft variation learn. It might be the issue.

vht

I didn't use gm knock sensors, I should have. When I put the crank sensor, factory gm, I tried relearning the sensor and it won't relearn. It says rpm not reached or something like that, it's been awhile. It's a snap on scan tool. May try again or find someone with a different scanner.

Rick Dorion

iTrader: (1)

On my 2006 2500HD I was getting P0300 at 100K and 180K miles. Doing a tuneup, etc didn't resolve. I did a CPS relearn in both cases and the issue was resolved.

The engine is a stock 6.0.

LS1Formulation

iTrader: (13)

I used a Snap-On scanner for mine as well, and I initially had the same problem. But mine was because I didn't follow the steps perfectly. As soon as I did them right, it relearned immediately. Try it again, it'll probably work.

Rick Dorion

iTrader: (1)

I used a chinese Xtool D7, I had to retry also. Reving it to the fuel shutoff gave me pause even though it's only 4K-ish or so and I didn't rev it high enough the first time.
Second time was fine and you can just hear the rpm's start to fall off.