2C31 DME Code

The Wanderer · 09-10-2019, 08:51 PM

Hey guys,

Emissions testing is posing as quite the dozy for me right now. I have a 2010 335xi which is MHD stage 2... so you know what that includes. These ** along with stage 2 shadow codes cause my catalyst to be incomplete, but I live in Utah and I am allowed to have one readiness monitor as incomplete. This leads to my first question - Is catalyst 'not ready' and automatic failure. (if so I can mess with trying to get a dp fix to work i guess)

Looking forward assuming it is not as Utahs website does not mention it is, my car is ready in every other category. However my DME is throwing the code - 2C31 - Oxygen sensor emission control. This code is only seen in the MHD app, it does not trigger any dash lights (I have found great threads in regards to this issue but would prefer to pass emissions now and deal with codes with time). Will this code be detected by emissions OBD II check and lead to emissions failure?

Thanks in advance!

The Wanderer · 09-10-2019, 09:17 PM

I have attached images of my MHD codes.

dpaul · 09-11-2019, 04:05 AM

I cannot answer your question with assurance because I don't know what might happen in Utah. However, in my state I believe that only the monitors are tested so if there is no CEL, and only one "not-ready" flag is present, you would pass.

But why don't you just fix what's wrong, then get inspected?

A log would be helpful in diagnosis but the obvious culprit is your bank 1 pre-cat O2 sensor. That said, problems with the post-cat sensor can also trigger the pre-cat 2C31 code because the post-cat sensor used for calibrating the pre-cat. You could use INPA to monitor the voltage for each sensor in real time. Or you could just replace them both, not that expensive or difficult.

The Wanderer · 09-11-2019, 08:29 AM

Thank for the response. I was thinking the culprit was the rear O2 sensors as well, as they could easily have been damaged along the way with the DP change. I do not have a the monitor section of MHD yet but have always wanted it so maybe now is the time. My situation seems very similar to Rushans in this forum -- https://www.n54tech.com/forums/showt...t=46890&page=2

Just was hopping to pass and have some time to trouble shoot properly rather than just buying new o2 sensors.

All other opinions on what might throw this code are still welcome!

09-10-2019, 08:51 PM	#1
The Wanderer New Member 0 Rep 11 Posts Drives: 2010 BMW 335xi Join Date: Jul 2019 Location: SLC iTrader: (0)	2C31 DME Code - MHD Stage 2 + Emissions Hey guys, Emissions testing is posing as quite the dozy for me right now. I have a 2010 335xi which is MHD stage 2... so you know what that includes. These along with stage 2 shadow codes cause my catalyst to be incomplete, but I live in Utah and I am allowed to have one readiness monitor as incomplete. This leads to my first question - Is catalyst 'not ready' and automatic failure. (if so I can mess with trying to get a dp fix to work i guess) Looking forward assuming it is not as Utahs website does not mention it is, my car is ready in every other category. However my DME is throwing the code - 2C31 - Oxygen sensor emission control. This code is only seen in the MHD app, it does not trigger any dash lights (I have found great threads in regards to this issue but would prefer to pass emissions now and deal with codes with time). Will this code be detected by emissions OBD II check and lead to emissions failure?** Thanks in advance! Last edited by The Wanderer; 09-10-2019 at 11:21 PM..
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09-10-2019, 09:17 PM	#2
The Wanderer New Member 0 Rep 11 Posts Drives: 2010 BMW 335xi Join Date: Jul 2019 Location: SLC iTrader: (0)	Images of MHD DME Codes I have attached images of my MHD codes. Attached Images
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09-11-2019, 04:05 AM	#3
dpaul Lieutenant Colonel 654 Rep 1,893 Posts Drives: 2009 E90 335xi, 2011 E93 M3 Join Date: Dec 2012 Location: Boston iTrader: (3)	I cannot answer your question with assurance because I don't know what might happen in Utah. However, in my state I believe that only the monitors are tested so if there is no CEL, and only one "not-ready" flag is present, you would pass. But why don't you just fix what's wrong, then get inspected? A log would be helpful in diagnosis but the obvious culprit is your bank 1 pre-cat O2 sensor. That said, problems with the post-cat sensor can also trigger the pre-cat 2C31 code because the post-cat sensor used for calibrating the pre-cat. You could use INPA to monitor the voltage for each sensor in real time. Or you could just replace them both, not that expensive or difficult.
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09-11-2019, 08:29 AM	#4
The Wanderer New Member 0 Rep 11 Posts Drives: 2010 BMW 335xi Join Date: Jul 2019 Location: SLC iTrader: (0)	O2 sensor Thank for the response. I was thinking the culprit was the rear O2 sensors as well, as they could easily have been damaged along the way with the DP change. I do not have a the monitor section of MHD yet but have always wanted it so maybe now is the time. My situation seems very similar to Rushans in this forum -- https://www.n54tech.com/forums/showt...t=46890&page=2 Just was hopping to pass and have some time to trouble shoot properly rather than just buying new o2 sensors. All other opinions on what might throw this code are still welcome!
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