Possible causes – Faulty front heated oxygen sensor– Ignition misfiring– Faulty fuel injectors– Exhaust gas leaks– Incorrect fuel pressure – Faulty Mass Air Flow (MAF) sensor Tech description There is a factory service bulletin for the following GMC models: 2000-2008 GMC Sonoma2000-2008 GMC Sierra2000-2008 GMC Yukon2000-2008 GMC Yukon XL2001-2008 GMC Denali2001-2008 GMC Denali XL2001-2008 GMC…