Does code p0301 have anything to do with replacing your air check system valve? on 2000 Cadillac Seville SLS

What is the point of a air check system valve? Will it make u fail inspection?

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.