P0300 random misfire trouble code

Fix a P0300 random misfire code on a GM or GMC vehicle

If you own a Cadillac, Chevrolet, or GMC listed below and have a P0300 code Service Engine Soon Light On, along with evidence of cylinder #1 and #7 showing spark plugs oil fouled or with cracked porcelain, read this post.

2007-2011 Cadillac Escalade, Escalade ESV, Escalade EXT with V-8 built prior to Feb 1, 2011
2007-2011 Chevrolet Avalance, Express, Silverado 1500, Suburban, Tahoe with V-8 built prior to Feb 1, 2011

2007-2011 GMC Savana, Sierra 1500, Sierra Danali, Yukon, Yukon XL, Yukon Denali, Yukon Denali XL with V-8 built prior to Feb 1, 2011

GM has issued a service bulletin #12-06-01-001 to address a P0300 random misfire trouble code, service engine soon light on, rough running engine, cracked or oil fouled #1 or #7 spark plug.

GM has determined that the positive crankcase ventilation PCV valve may pull in too much oil vapor into the engine near these two spark plugs. GM has modified the valve covers and installed baffles to prevent this additional oil vapor from being injected into the cylinders.

Order valve cover 12570427 for vehicles 2007 & 2008 models, and 12642655 for 2009-2011 models. Order valve cover gasket 12612045 for either cover

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