NOX Sensor Catalytic converter / Reducing agent active tank...
 

Hi guys, I have a 2012 E70 35Diesel and had intermittent CEL on so I bought an Android app called i-vini bmw scanner and found these error codes (took a screenshot). The i-vini was convenient and I was able to reset the CEL all the time when it came on. However, I noticed that now the CEL lights up more often than before so it's starting to worry me. I have already refilled the DEF (about 4 liters because that's what's left in my supply).

Does anyone have the same problem? Maybe you can share your experience on how to finally/permanently solve this issue?

The sensor is built-in into the tank and it is not rare that these fail. As the error suggests, there is a problem with the sensor. There are ways to test the sensor with a multimeter.

Thanks lanbrown! Would you know where that sensor is located? Can I do a DIY and just replace it?

As I stated above, the sensor is built-in to the tank. You might try cleaning the tank out as sometimes that does help get the sensor working. BMW only sells the tank and sensor together. Some have disassembled the tank and repaired the sensor. So you might want to search this board and other BMW boards for what others have done.

Take a look here on how to test and repair the DEF sensor: X5 35d CEL P205b - Page 4 - Bimmerfest - BMW Forums. What is described there does not deactivate the sensor in any way. It simply fix the self diagnostic circuitry of the sensor which is prone to failure.I would start with that.

Regarding the other code, here's a couple of thoughts:
1) Take a look at this: Reducing agent metering valve actuation fault. - Bimmerfest - BMW Forums. It describe how to diagnose the metering unit which too can fail. May not be your problem, but removing, testing and cleaning the metering unit could help.
2) The NOx sensor module is located right below the drain of the A/C. I believe I read someone who was having issues with the NOx sensor and the reason was corrosion on the actual module, not the sensor itself. Take a look here: A/C drain location - Bimmerfest - BMW Forums. That's what I've done on mine after noting corrosion starting to appear on the module and the crossmember. May be worth a look for you and perhaps remove the connectors and clean them with contact cleaner. But it may be completely unrelated.

Oh, I and others would really appreciate it if you could report back the results...

ZeraTre / lanbrown - thanks so much. Will start working on this and will post the results.

FMJ- "phillipines" as in "no warranty and no decent BMW dealers"?

Report back- good advice so far

Hi ard - I got my bimmers from an importer. Both my BMW vehicles were inported from the US so this means I do not enjoy any warranties from local dealers here. The US versions of BMWs are better than the local versions because they come in with all options. The local ones are overpriced and come with almost bare options. Unfortunately, in this particular case, there are no locally released BMW's that use DEFs therefore they cannot service and address this particular issue (Philippine emission regulation is almost non existent - no regulations on Diesel soots unlike the US). I had to ship DEF bottles from the US that took months to arrive because they were shipped by sea. Hence, I'm left with DIYs for this. Trying to search on the web how to take down the tank and sensors before I order from Pelican :-) I hope this paints a clearer picture on why I choose to refer to the threads and not go to the dealers. But thanks for the concern there!