How can you figure out what CAT is going out?

[sock_s]

Hey All,

I have a 2000 Sentra GXE 1.6L. I get an engine code telling me the Cat is going out. What tests can I do to determine if it is the tail end or the manifold going out?

Thanks for the help.

[Chiquae07]

i hope you dont have the gxe with 4 o2 sensors...

get the code cleared and see what comes back up. you have one in the header and one after the midpipe.

my guess from lookin at the FMS, is bank 1 sensor 1-2 is the one above the precat in the header, and bank 1 sensor 3-4 is the one after the cat in the header. you shouldnt get a cel for the cat under the car.

[nismo_pilot]

you have the 1.8l qg18de.... telling us the code is for the cat going out is vague, give us the code so we can help, as was mentioned earlier sensor 1-2 are the mixture feedback sensors, and 3-4 are the catalyst efficiency monitors, the latter are worthless but the first two can ruin your gas mileage, you should be able to make a diagnosis based on your recent fuel economy