rear o2

[gotboost3]

if im running no cat should i leave the rear o2 plugged in or unplugged? dont i need to tune for no rear o2? right now i have it plugged and tucked away....when i left it unplugeed i got ****ty mpgs....but i think my front o2 sensor was going bad also at that time lemme know if i can unplug it...

[Bio248]

you need an o2 simulator or youll always get a bad cat code. the rear o2 has nothing to do with gas mileage, just to tell if the cat is bad or not.

[blueguy]

^^ It does. If it is a '01 or newer.

[Bio248]

for real? news to me.

[FoSHO99]

I've been battling it for a while with my 01, finally just did a full write with a 2k .bin and so far so good. The emulator either failed or didn't do its job, but it would still flash like it was working and gas mileage was crap.

You can also leave the rear 02 plugged in and hang it somewhere, as long as it gets a signal its working it should not throw a code or alter your gas mileage that way.

[gotboost3]

so if i have a 00 can i unplug it with out problem?

[blueguy]

Sure...just have someone eventually delete the code permanently IMO.