Looking for any insight. I have an 05 cooper s. It's running equal length headers and test pipe. Rear o2 has a simulator installed set at .9v. But I'm still getting a post catalyst system lean code. I've tried at different Mv and noting changes. I can clear the code and drive the car as long as I want and it stays off. As soon as I cycle the key the code returns. I've read could be intake or exhaust leak. But having the o2 simulated that should matter. Fuel trim for the rear senor stays within 2/-2. Front sensor about 5/-5. Could it be an ecm issue?

 

We had a car in the shop that we went through and resealed everything from intake to exhaust and the car still had the P2096 code, after that we started testing O2 sensors, engine harness, updated the ECU, even swapped a known good engine harness into the car and still had the code. We ruled everything out down to the ECU and that is where the customer drew the line, as it was more than he wanted to spend on a possible fix, but there were some cars that had the ECU silently replaced at the dealer early on to fix this issue, as many people called it a "ghost code" with "no real fix". To my knowledge that car is still out there, but I doubt the issue was ever resolved.

 

So no real fix huh? Do you think throwing an o2 sensor in the rear would fix anything? I've been calling around to see if anyone can reset the adaptive parameters. But no one in my area even knows what I'm talking about.

 

I wouldn't condone throwing parts at the car without diagnosing the problem. Like I said, we had countless hours involved in what we did as well as some part cost to the mix as well.

If you can find a shop with access to a Snap-on Verus tool I believe that will reset the adaptations, otherwise you'll need to find a Euro shop or the dealer.