o2 simms with catted ypipe
 

After I install my Pacesetter LT with catted y-pipe do I also need O2 simms for the former rear sensors or just the extensions to place the sensors in the header bungs?

are you getting a tune?

you need both well at least some O2 extensions for the plug at the collector of your lt's.... rear O2's you can either get simms, tune 'em out, or use them for your cats

you would only use 02 sims if you removed the cats, just buy some extensions and place the original ones in the new y-pipe.

So I can just drill a hole in the y-pipe after the cats, weld in bungs and use the existing rear O2 with extensions then?

My new catted Y came with 02 bungs in it I just had to screw my old ones right in.

If the y pipe didn't come with bungs for the rear o2s, then just use simms (or have the code tuned out, either way works)
For the front, you'll need either extensions, or 2 bosch 13111 (the wire on this o2 is long enought to reach without using an extension)

What do you do if you dont use a catted y pipe? do you unplug the rear o2 sensors?if so will the check enigine light go on?

Using the rear O2 sensors, even with cat's, will probably still trip your SES light. Some people luck out and don't get coded, while most will be coded. The rear O2 sensors are set to accept values between certain parameters without setting a code. Aftermarket cats may not operate between them, and you'll be screwed. The only thing to assure you no SES light is to have the codes tuned out (see the FAQ). Second best way is to run O2 sims (which don't work every now and then). Third way is to plug the rear O2 sensors in after the cats and hope for the best.







Check the FAQ at the top of this section.