Solved- 5.3 Vortec P0300 & P0302 - 2013 Tahoe

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Just00Jake

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I have a 2013 Tahoe LS with 190000 miles on it. I started out with an intermittent rough idle. Very quickly it went to a P0300 and then to a P0302. My exhaust was to rich.My traction control and stability were both off. I had rough shifting and a check engine light. I already planned on a tune up so I changed plugs and wires (Delco Professional Iridium). Checked for vacuum leak. None found. Checked injectors. All were fine. No change. Changed all 8 coil packs. No change. I did a compression test and ended up more confused. Did a leak down test. Everything appeared Ok. I was basically told by a few mechanics that it's probably a broken out weak valve spring. I pulled the passengers valve cover and everything looked good. Push rods, cam lobes, rocker assembly. So I changed the intake and exhaust valve springs. Put everything back together. No change. After reading every post and watching every video that I could find on anything even close, I started reading GMs service bulletins. I can't across this (picture attached). I made 1 last attempt at a fix before I figured I needed a valve job. I bought Seafoam top engine and valve cleaner for $18. It took about 25 minutes to do the whole process. It seemed so easy that I figured there was no way this would be the fix. It worked. I reset my ECU by sitting the positive and negative called together (disconnected from the battery of course) I reconnected everything and re programmed the ECU. Check engine light went off, traction control came back on, stability came back on, hard idle and hard shifting went away. It was a miracle. It was the simplest fix after all of the time and money I've didn't.Screenshot_20230116-210628.jpgScreenshot_20230116-210709.png Thank you Chevy Gods
 
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Just00Jake

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Thanks for the info. It helps a bunch. share what the process was with the Seafoam, please.
It was actually Seafoam Top Engine and Valve Cleaner, it was around $19. It came with a skinny straw and an elbow to get around the corner of the throttle body intake tube. You have to get your engine to running temperature and then idle it at 2000 rpms while introducing the cleaning spray into your cold air intake. I understand if too much is sprayed too fast then u5 risk locking up the cylinders up with a vapor lock. It took me about 7 minutes to empty the can. Then you choose everything up (while the engine is still warm) and let it stew for 10 minutes. While this was happening I was reseting my ECU. After the 10 minutes you want to drive out hard to get the carbon out. After having the permanent p0302 code for 10 months while I tried to figure it out, it just disappeared. I was getting a p0219a immediately after spaying the cleaner btw.
 
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Just00Jake

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I do want to add... Just so no one thinks that they caused other issues... It is very likely that you will get a P0219a or P0219b code and the check engine light after completing this process. Mainly because the cleaning solvent burns with the fuel immediately after and gives your O2 sensors a bunch of confusing readings which caused the codes. I just waited until the next day and plugged in my computer and cleared then and they were gone.
 

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