Seaneezy

Corporal
Mar 12, 2018
130
34
0
Ride
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.
 

topher335

Lurker
Jul 6, 2017
24
9
0
Ride
E92 335i
I have a DP fix installed as well to pass smog
Your fault conditions for fault code 2CFE are
"Excessive trim controller deviation; behind catalytic
converter sensor voltage outside range around trim
controller specification point with trim controller active
(approximately < 0.2 V or approximately > 0.9 V) "
Put your real CAT back on and the fault code will go away!
They are caused by your rear oxygen sensor because the
aftermarket catalytic converter are shit compared to the OEM!
Or learn learn how to program :smirk:
 

topher335

Lurker
Jul 6, 2017
24
9
0
Ride
E92 335i
He may but the DP fix and/or aftermarket CAT will cause faults like this.
Plus the fault is for too rich not too lean
 
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Seaneezy

Corporal
Mar 12, 2018
130
34
0
Ride
e90 LCI 335i
Any chance you have an exhaust leak?

Filippo
possible, not probable, replaced all the gaskets... BUT, when I start it up in the morning and any HVAC running it will smell like straight oil/gas, signifying a valve cover issue as far as I'm concerned, leak checked the cover and it turned out fine so that's another issue in my car i have no idea what the fuck is from.

Your fault conditions for fault code 2CFE are
"Excessive trim controller deviation; behind catalytic
converter sensor voltage outside range around trim
controller specification point with trim controller active
(approximately < 0.2 V or approximately > 0.9 V) "
Put your real CAT back on and the fault code will go away!
They are caused by your rear oxygen sensor because the
aftermarket catalytic converter are shit compared to the OEM!
Or learn learn how to program :smirk:
Good point, at this stage I'm willing to put it all back to stock with the 15 hours of labor it will take to take it back there. I'm also running a pretty aggressive street tune that is probably out of date. I'll go boring mode for a month to let the car fix its own shit as BMW's tend to do.
 

Seaneezy

Corporal
Mar 12, 2018
130
34
0
Ride
e90 LCI 335i
possible, not probable, replaced all the gaskets... BUT, when I start it up in the morning and any HVAC running it will smell like straight oil/gas, signifying a valve cover issue as far as I'm concerned, leak checked the cover and it turned out fine so that's another issue in my car i have no idea what the fuck is from.


Good point, at this stage I'm willing to put it all back to stock with the 15 hours of labor it will take to take it back there. I'm also running a pretty aggressive street tune that is probably out of date. I'll go boring mode for a month to let the car fix its own shit as BMW's tend to do.
Putting it back to stock worked, the codes are gone and readiness monitors are ready. I guess there wasn't much point in spending $1000 extra to get shitty cats on my downpipes (AR-design catted :mask: )