[Chrisguilday]

Hey guys, I just installed a catless DP on my 2011 335i.

When I swapped the 02 sensors over I noticed the post-cat sensor was very white, and the pre-cat one was mostly blackish with a small area that was white.

I thought about replacing them, but I wasn’t in a position to do so as my car was very far away from home at my buddies house, and I needed to get back home (was 3 AM by the time I finished the job, it was hard as hell to replace the cat, was exhausted and just wanted to be done)

So my question remains: Is that normal? Or is it a sign of a 02 sensor that’s going bad? Or does that mean my engine could be running lean, etc?

After I installed the cat I tuned it to stage 2+, and it runs perfect so far. No codes, no misfires, etc. Am I good to go?

Also, shouldn’t I be getting a code from the post-cat (down stream) 02 sensor? Both sensors are plugged in, but doesn’t the post-cat 02 sensor check to see if the catalytic converter is working? Well I obviously don’t have a cat anymore, so shouldn’t it be throwing a code? I have no codes at all.

[icoutino]

it´s normal, the second o2 sensor its clean because it was after the cat, with the catless downpipe you should have a check engine ligth, but surely the stage 2+ take care of that.

im not an expert, but im dealing with that same problem but with out the stage 2 repro, so I have the check engine light in my dash.