92 chev suburban 122000 miles failed nox portion of ca smog replaced egr valve got worse results on retest could o2 senser be the culpret
Aug 6, 2011 at 1:50 AM
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SATURNTECH9
CERTIFIED EXPERT
30,869 POSTS
For nox i woud say look hard at the egr system you replaced the egr valve but did you make sure the egr system worked and the intake and exhaust ports to the egr were clear and not clogged?Do you have any codes?have you checked for codes yet?