P0300 error 200 suburban

[keith32]

I had a really bad incident this weekend, I was stuck in traffic jam idling for about 2.5 hours, when my 2000 burban with 130,000 miles starting to sputter but did not stall. It ran rough at idle for about 5 minutes, long enough to get the heart pounding!! The Check Engine light blinked. then it stayed on after the idling smoothed out. I took it the next day to autozone, and they checked the codes and it gave the P0300 error, Spark plug mis fire. Plugs and wires were changed back @ 100K mark. The light stayed on, as they didn't clear the code unless I bought parts. But I wanted to investigate further. After driving around town on sunday, It has not repeated the problem again. (touch wood). and the CEL did go off by itself. Has anyone ever seen this, and should I be worried??? What is the P0300 code, does it pinpoint the problem to a bad Plug, or is could it be a variety of things? Please email... Thanks

[maxwedge]

Random misfire on multiple cylinders, cannot really be traced if it cleared up, possibilities such as a plug, wire, cap, or injector misfire under the extreme conditions you had that day.

[wafrederick]

It is the catalytic converter.GM has problems with them.Had one in,but a 2002 GMC Sierra that was another dealer's after replacing the engine.It came down to the catalytic converter and it was bad,heard a whistling noise from it.The dealer bought a new one($500.00) from the dealer that owned the truck.After putting it in,the missfire was gone and ran really good after that.

[maxwedge]

Usually a bad cat that accompanies a misfire code demonstrates other symptoms such as the whistle, noticeable loss of high speed power and cat efficiency codes.

[thradke]

Sounds a lot like the first time I noticed anything wrong with our '00 Suburban. It also logged the P0300 Random Misfire code, as well as the Catalyst Efficiency code (P0420) I have a lengthy post of the various checks I have made so far on this site. It's starting to look like the CATS though...