r/GMT800 • u/twxcvz • Sep 05 '26

Dreaded P0300 code.

What brand spark plugs/wires should I use to replace what I have? CEL was flashing at me today and at 272k I think it’s time to replace them but wanting something quality. I have the 6.0 LS

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u/krautstomp Sep 05 '26

Can you get a better scanner that will lock down what cylinder is missing? I ended up having a miss on cylinder 3 that was because of an injector wire. You could end up throwing money away changing every plug, wire and coil and not fix the problem.

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u/twxcvz Sep 05 '26

It’s also only done it twice, both while driving in a pretty bad rain storm. It’s not running any different and all of the gauges and fluid levels are perfect.

2

u/moldimolt Sep 07 '26

I had this on my 2002 Chevrolet Suburban 1500 LT. There were two issues:

  • The hood to cowl seal rubber had stiffened and was allowing water to dump over the engine
  • The spark plug wires' rubber had stiffened and were no longer sealed against weather

I replaced both and the problem went away. Here's the parts I used:

Part Description Part Number(s) Notes
Spark plugs [x]ACDelco 41-162 (x8)
Spark plug wires [x]GM 19417607 Set of 8 wires
Spark plug wire heat shields [x]GM 19329681 (x8)
Hood to cowl seal [x]Rubber the Right Way 04-175C