2000 Cadillac Seville SLS Q&A
2000 Cadillac Seville SLS Question: Does code p0301 have anything to do with replacing your air check system valve?
No, P0301 is a misfire cylinder #1. The secondary air system is part of the emission controls and it delivers air to the exhaust manifolds during a cold start to reduce hydrocarbon emissions and assist in getting the catalytic convertor to work faster. - cardocIII