- Mar 12, 2018
- e90 LCI 335i
No idea what the hell is causing this anymore. The codes were involving both post-cat o2 sensors and pre-cat o2 sensors with lamba/mixture errors. I replaced both back o2 sensors and the front o2 sensor that was giving codes, they still appeared. At this point I assumed it had to do with my car misfiring, I replaced all 6 ignition coils and plugs, my bank 2 injectors (bank 1 is relatively new), and the code is still showing up around 10 minutes after clearing it. I have AR-design catted downpipes, the cats are clean not clogged and I have a DP fix installed as well to pass smog, but these codes are obviously preventing that. Valve cover gasket was replaced 1500 miles ago, it was tested for leaks and proper application. I had an oil leak from a mechanic who forgot to tighten my oil pan bolts, but that was fixed a while ago. Downpipe gaskets, fitment refreshed. PCV system was refreshed as well. If anyone has any idea of how to move forward with this let me know, I have done all the research these BMW forums have allowed me to do.