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Reload this Page Recurring Code: 2C31 (Lambda probe in front of catalytic converter, trimming control)
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rleroy4298 rleroy4298 is offline
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Default Recurring Code: 2C31 (Lambda probe in front of catalytic converter, trimming control) - 06-06-2015, 04:55 PM

I have been getting the referenced code consistently for a few months now and was hoping to get some feedback as to a likely root cause. For reference, I was running my car (details below) with ~E60 (E85 Backend Flash) back when this first appeared, however, the past month has solely been 93 octane without any backend flash on various maps to see if I would continue having this issue.

2C31 Code Triggered Conditions:
In these recent months, I have noticed one thing that seems to trigger the code pretty easily, and that is when I am cruising around (~40mph up to ~60mph) and let off the gas, or reduce it. I can then feel a bit of roughness/hesitation in the pedal until I clear it. There are also the occasional times when I've gunned it on the freeway that has triggered it, but I've lately tried to restrain from doing that. Oh, and I was running ********* for about a year before any of this started without triggering 2C31. Anyways, since this code normally appears under normal driving conditions, I've attached a log doing just that. For reference, the car was free of faults at the start of this log, but somewhere within, 2C31 was triggered.

Link to Log

Hope this information can supplement anyone's review of the log, or their own personal experience with a similar problem, to help me get this sorted out. Thanks for your help in advance!

Car: 2010 E90 335i
Mileage: 65k mi
Current Power Modifications:
Fuel Used: 93 octane
BMS JB4 G5 ISO (latest firmware; 29)
BMS DCI
BMS Chargepipe
VRSF 5" FMIC VRSF
********* ***
Fuel-It Stage 1 LPFP Upgrade
Alpina B3 Flash
Rb PCV Valve
Walnut Blasting completed at 57,500 mi
New Spark Plugs & Coils 64,000 mi
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File Type: csv 2015-06-05 14_36_55.csv (132.4 KB, 411 views)
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Terry @ BMS's Avatar
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Default 06-06-2015, 06:03 PM

It's an O2 sensor issue. If you have a wired in ***** module remove it and throw it in the trashcan where it belongs. If not, then perhaps a faulty or mixed up rear sensor.


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Default 06-06-2015, 06:20 PM

Quote:
Originally Posted by Terry @ BMS
It's an O2 sensor issue. If you have a wired in ***** module remove it and throw it in the trashcan where it belongs. If not, then perhaps a faulty or mixed up rear sensor.
Thanks for the quick feedback. Would this not be the front sensor though (Item #1 in attached drawing) based upon the code's verbiage? I actually did order a replacement O2 sensor the other day (Item #1 in attached drawing) so if it is the rear as you say, I hope these 4 sensors, although different part #'s, are all interchangeable...and I hope this is the solution as I've heard about this being related to leaks, etc.



Also, ya I've never had the module you're referring to installed on my car.

Thanks again, and when you get a chance, could you add some additional reference to the sensor location?
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Default 06-06-2015, 06:21 PM

I don't know on the sensor. Any variance between front to back and bank to bank could trigger the fault.

Putting the small black subconnector back to stock will also eliminate the JB4 from possible interference.


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Default 06-06-2015, 06:25 PM

Quote:
Originally Posted by Terry @ BMS
I don't know on the sensor. Any variance between front to back and bank to bank could trigger the fault.

Putting the small black subconnector back to stock will also eliminate the JB4 from possible interference.
Sorry, but which small black sub-connector?
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Default 06-06-2015, 06:28 PM

The small black subconnector the JB4 intercepts.


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Default 06-06-2015, 06:44 PM

Quote:
Originally Posted by Terry @ BMS
The small black subconnector the JB4 intercepts.
Just to confirm, but this one below? If so, do I leave the rest of the JB4 all connected as it normally would be? Apologize, but I've just never seen anyone reference this method for anything in the past.

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Default 06-07-2015, 11:47 AM

Yes, the small black connector with the red wires. Leave everything else as is.

Reset your adaptions (1/7) and see if it goes away for a while. As said, if you have the ** fix...ditch it.

As your log continues, you develop a delta in AFRs between banks. There is an issue there. Possibly the rear O2 sensors swapped?



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Default 06-09-2015, 03:46 PM

Quote:
Originally Posted by Steve @ BMS/Fuel-It!
Yes, the small black connector with the red wires. Leave everything else as is.

Reset your adaptions (1/7) and see if it goes away for a while. As said, if you have the ** fix...ditch it.

As your log continues, you develop a delta in AFRs between banks. There is an issue there. Possibly the rear O2 sensors swapped?
Hey Steve, thanks for the feedback. Once I remove the JB4's small black sub-connector, do I leave the stock small sub-connector unplugged (one side of that slider left empty), or do I plug the stock small sub-connector into that spot of the slider and connect it to the normal, original (w/o JB4) small connector? Kinda confusing to put into words, but I just wanted to confirm before moving forward.

Once done, then log to see if the 2C31 code comes back or there continues to be a delta in the AFRs? If not, problem likely solved, but pending no change, then see if the rear O2 sensors are swapped or if an O2 is just faulty?

Really appreciate the help!
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Default 06-09-2015, 06:41 PM

Yes, you'll need to plug the stock connector back in to it's original location. If you still get the 2C31 codes then you know it's not JB4 related and you'll need to continue trouble shooting. Definitely do the 1/7 command if you haven't already and verify the delta between banks is gone.



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Default 06-10-2015, 08:27 AM

Quote:
Originally Posted by Steve @ BMS/Fuel-It!
Yes, you'll need to plug the stock connector back in to it's original location. If you still get the 2C31 codes then you know it's not JB4 related and you'll need to continue trouble shooting. Definitely do the 1/7 command if you haven't already and verify the delta between banks is gone.
Thanks, Steve. I went ahead with this and reset adaptations. I plan to drive it around a bit before grabbing another log so that things can adjust...also in the past, its taken some time for the 2C31 code to reappear whenever I reset the adaptations. In regards to monitoring AFRs, what delta should I consider to be out of the ordinary? Wasn't sure if there was naturally any deviation between banks or if they literally mimic each other.

Thanks again, and I'll capture a log, and post it later today.
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Default 06-10-2015, 08:47 AM

They typically mimic each other. When there is a delta, in my experience it's been caused by ** fix or something throwing the calibration out of adjustment.



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Default 06-10-2015, 10:41 AM

After putting the small black sub-connector back to stock and resetting adaptations, I was able to capture 2 additional logs today (similar driving conditions). The first log began after I had driven ~7 miles since resetting, with the second wrapping up after a total ~20 miles. The 2C31 code did not appear during this time, but I worry that I just didn't give the adaptation process enough time and that it eventually will...how long does the adaptation process usually take?

In regards to the 2 newest logs (Datazap link below & csv files attached) compared to the original log (prior to connector change & adapt. reset), I did notice that the maximum AFR delta decreased slightly. I also noticed that the average AFR delta in these latest two logs hovered around 0.120, while the original log contained an average delta of 0.283.

Log 2
Log 3

Anyways, please have a look when you get a chance and let me know your thoughts, and recommendation on a path forward. Thanks again.
Attached Files
File Type: csv Log 2.csv (263.8 KB, 365 views)
File Type: csv Log 3.csv (345.7 KB, 374 views)
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Default 06-10-2015, 11:36 AM

Need longer logs for viewing and adaption. 3rd gear 2.5K to at least 6K or so would help.



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Default 06-10-2015, 07:09 PM

Steve, I was able to grab two additional logs this evening with the first (Log 4) containing 2 pulls in 3rd gear on Map 2.

The second (Log 5) was soon after, however, in Map 5 and also contained 2 pulls (1st in 3rd gear; 2nd automatically downshifted from 3rd to 2nd). Towards the end of this second pull, the code “2D2E Angle of throttle valve – intake pipe underpressure, correlation” popped up which I had never seen before. When coming to a stop, the car would stutter/surge and actually turned off once or twice. I also noticed that by the end of this log, the Avg Ign had dropped down to 1.1 and FF/Wastegate Adaptation had jumped from 80 to 107. I never once saw 2C31 in either of these logs, but it still may be too early. Note that I forgot to mention that all of these logs (2-5) were with the E85 backend flash uploaded running E50.

Based on this latest data, any further thoughts into the 2C31 & AFR issues? …or any insight into this latest fault code thrown into the mix as I was unable to find much by searching. Thanks again for the continuous support!
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File Type: csv Log 4 Map 2.csv (255.5 KB, 400 views)
File Type: csv Log 5 Map 5.csv (220.6 KB, 376 views)
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Default 06-11-2015, 01:37 AM

AFR's look fine and track well. FF will adjust and looks fine and the logs look pretty decent. When your car is acting like that, take a log.



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Default 06-11-2015, 08:10 AM

Quote:
Originally Posted by Steve @ BMS/Fuel-It!
AFR's look fine and track well. FF will adjust and looks fine and the logs look pretty decent. When your car is acting like that, take a log.
Steve, attached are two logs that I took driving around. As mentioned, the harshness and shaking from that code is really noticeable at idle. I had to slightly press down on the pedal a could times within the log (at a stoplight) to reduce the shaking.
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File Type: csv Log 6.csv (232.6 KB, 375 views)
File Type: csv Log 7.csv (223.4 KB, 392 views)
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Default 06-11-2015, 11:33 AM

Grabbed one additional quick log (Log 8) representing the harsh idling. At the tail end of it, a misfire in cylinder 1 popped up which is now new as well. I replaced the plugs less than a 1000 miles ago and the injectors aren't too old either, so I'm going to throw a new coil pack in tonight to hopefully mitigate this new problem. Any ideas though on the 2C31 & 2D2E fault codes?
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File Type: csv Log 8.csv (211.9 KB, 352 views)
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Default 06-11-2015, 06:08 PM

Steve, any thoughts? I replaced the coil packs this evening, but still no improvement.
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Default 06-12-2015, 08:00 AM

Anyone?
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Default 06-13-2015, 12:14 PM

Steve, any thoughts?
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Default 06-14-2015, 10:46 AM

You are running very lean and your trims are maxing out.

What fuel are you running and what flash?

Any work done on the car recently?



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Default 06-05-2017, 09:56 AM

did you ever fix this? im getting the same code and dont know if its actually the front sensor or just the variance between front and back.
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Default 12-02-2017, 05:53 PM

Quote:
Originally Posted by Massius
did you ever fix this? im getting the same code and dont know if its actually the front sensor or just the variance between front and back.
Sorry to bring this old post but Having the same and both front and read sensor replaced and still showing 2c31 and some other times 2c32 and sometimes both,

I guess it's JB4 firmware or BMS flash related I will be trying to roll back in flash and firmware to try to trace back.

Something to do with the firmware or flash for sure as I checked all ** gasket for leaks and replaced O2 sensors and it's not swapped


09 E92 335i - Hot-Climate Middle East package, M Sports suspension, 19" Rims, 6AT fully built internals, bushings, raybestos clutches and sonnax with xHP stage 3, Differential lockdown, New RB Turbo CHRA, JB4 - Map 3 70 adder with N20 TMAP - MHD BMS Race Flash with Tuned Duty Bais and PID - BMS Oil Cooler Valve - RB PCV - K&N DCI - AFE Air Scoops - 98 Super Fuel - WAGNER FMIC - 3" down's, RB Inlets- BMS charge pipe With Tial BOV - BMS Meth Kit with FSB, 30/70 Water/Meth on CM12 nozzle
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Default 02-27-2018, 08:53 PM

Quote:
Originally Posted by Rushan
Sorry to bring this old post but Having the same and both front and read sensor replaced and still showing 2c31 and some other times 2c32 and sometimes both,

I guess it's JB4 firmware or BMS flash related I will be trying to roll back in flash and firmware to try to trace back.

Something to do with the firmware or flash for sure as I checked all ** gasket for leaks and replaced O2 sensors and it's not swapped
Did you ever resolve your issue? I'm having same issue after ** install, all the O2 sensors are correct. Resetting adaptations will work car will drive great until the codes come back. Tending to think its DME or JB4 related at this point...
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