B1 S1 is pre CAT. B1 S2 is post CAT.
O2 sensor readings used in fuel mixture by the ECU are the ones in the manifold before the CAT. The ones after the CAT are used as a reference to ensure the CAT is working correctly and have no direct relevance to fuel/air mixture.
It would seem you've at...
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.