Engine Mechanical problem
2007 Hummer H3 6 cyl Four Wheel Drive Automatic 78000 miles
2007 Hummer H-3 code issue unable to clear code po411 Reads secondary air inadequate upward flow #1. Replaced valve then reset code code then read po411/po418 issue came about around December 2009 to present ran diagnostics relay, pump, pressure, sensors read okay still unable to pass N.Y. Inspection. Vehicle runs fine any suggestions
I don't know if this will help or not but it tells which codes are set and maybe you can check, but from the manual i have it says to much or a a voltage problem or a ground problem but, it could also be a bad connection as well.......