2 DTC codes P0456 and P2196. Car runs fine. Can't pass emissions because check engine light is on.

Question

I want to pass emissions and find out why my check engine light came on with these codes.  Car runs fine.  We've had a very cold winter.

Answer 1

P0456 Evaporative emission leak (very small)

P2196 02 sensor biased ( signal rich)

You can relate these 2 code together , usually a very small evap leak deal with the fuel cap not sealing correctly or even loosely secured. For P2196 this is a lean fuel trim condition. vacuum hose leaks can and do cause lean condition , for yours  there is not much vacuum hoses that can cause a lean code, but there is a purge valve that can leak these are seen with Mazda and Ford and Mercury , a small leak at the purge set a P2196 and a EVAP code.. These code are very often seen together, the fix replace the purge valve.