cat back o2 sensors

[pete2528ca]

I know that the two o2 sensors after the manifolds help the fuel air mix, but what do the ones behind the cat. converter do? I've read that they only tell you when the cat. converter is pooched...

is this true?

Pietro

 

[joey]

That is basically correct, they just read if the Cats are doing their job. IMHO, they are very expensive Cat testers.

Maybe that is why I am working to eliminate them....$300 savings since I will not buy those 2 - O2 sensors.

 

[discomike]

They are to check the cats and they can also restrict fuel, hence power and economy, if the 2 front O2's are not doing their job.
Mike J.