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35d 4BCC- Reducing Agent Passive Tank Sensor Failure

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CEL light came on and with Carly adapter I found it's 4BCC- Reducing Agent Passive Tank Sensor Failure. I further ran a report on active and passive tank DEF level and I have 10% on passive and 43% on active.

Called up local SA this morning and they are saying passive tank replacement is covered under 7yr/70k miles whereas 3-4 months ago when I had my EGR cooler replaced ($1450) service manager confirmed that passive tank is now covered under 10yr/120k miles warranty. Local SA is refusing to honor 10yr/120k passive tank replacement warranty.

Please advise.

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Update:

Good news: I got passive tank replaced at no charge under 10 yr/120k extended warranty and $0 diagnostic feee. Attached is an image of work order.

Along with passive tank replacement they also did two recalls - Takata airbag for front and idler pulley.

Bad news: I ran a quick Carly diagnostic before leaving service center and found out 10 error codes (some listed below) stored all related to steering. I have a feeling when they replaced the airbag they probably did not follow proper procedure afterwards. I immediately emailed my SA with screenshots from Carly with error codes as he was gone for the day.

Errors:
006EC4 - Steering angle sensor
0055C3 - No DXC target torque setting
0055D0 - CAN message steering wheel angle, C4
00A55F - HW error steering column switch (LSS)
009CB1 -
00AA1C - Emergency speakers: interruption
00E2D6 - 0x330 Mileage flawed

Any advise?

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Try to reset the steering angle sensor (google it), otherwise they F'd up up the sensor and get ready to battle your SA again.

https://www.bimmerfest.com/forums/showthread.php?t=1324021

I think I'm going to pass on the airbag recall.....
Thanks for tip. I did google and that is exactly what SA advised when he returned my call this morning. SA confirmed that there will be no issue of DSC or any other light coming on as these error codes are because of battery been disconnected while performing airbag replacement. SA confirmed they did perform reset of steering angle sensor and don't have to worry on the error codes showed and confirmed that there are no CEL lights and to ignore error codes.

Thanks.
Try to reset the steering angle sensor (google it), otherwise they F'd up up the sensor and get ready to battle your SA again.

https://www.bimmerfest.com/forums/showthread.php?t=1324021

I think I'm going to pass on the airbag recall.....
Hey guys, I am getting this error code and upon investigation of the passive tank one of the sensors has some crystallization on the contacts. Photo attached for reference. Any thoughts - should I try the resistor install to the connector?

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Added the resistor but cel is still on. May need to reset the ecu, will do when I get my carly this week and will advise.
Resistor worked, coded cleared itself. Better than spending 4k Canadian on a new tank!
I am fighting with my SA about this currently on my 2011 X5d. They are telling me the passive tank is not covered. I got a card in the mail about this being now included in the 10/120k for my X5 a few months ago, but I cannot find the card anymore. Is there a document or SI that I can reference for the passive tank? I called BMWNA and they also said it isn't covered, but wanted me to send a photo of the card..I don't see it on BMW-RP for my VIN.
Check www.bmw-rp.com with your vin. It should be in that list if it applies to your car.
It isn't, I already checked. I'm not taking that as truth though. I got the letter in the mail, I just can't seem to find it.

Sent from my iPhone using Tapatalk
Check www.bmw-rp.com with your vin. It should be in that list if it applies to your car.
I am getting a 4BCC code for my passive tank sensor. I checked bmw-rp.com and saw some items related to scr: supply module and active tank. Does this mean that I'm not covered? I attached a screenshot. There's also a few other items.

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I am trying to "fix" this myself with a resistor. I am adding a resistor between the blue and black wires that I believe lead to the top of the tank and is for the level sensor for the passive tank. (my code is the 004bcc). I get a 10k OHM resistance before applying my fix. When I add the resistor inline, I get 5k ohm. I have cleared the code with Carly and waiting for it to return.

Anyone ohm these blue and black wires just to verify? What should a good sensor ohm at? I'm just not sure this will fix my issue when I was getting a 10k ohm reading prior to the fix. If it matters, my resistors are 10kohm, 1.8watt



If you are doing this yourself, I found it easiest to pop the signal magnifier off the side of the tank (slide catch on the bottom one way or the other and push box upward). Then you can better see how the connector pictured below comes off it.

Thanks for any help! Want this CEL gone and am not willing to pay the dealer $2500.
The sensor you tried to "fix" was likely fine.

There are 2 sensors, full and empty. When immersed in DEF the sensor will be low resistance (a short). When not immersed the sensor should be 10k ohm.

You might want to check the resistance across the other 2 wires. If it reads "open" then install a 10k ohm resistor across those wires.
...I get a 10k OHM resistance before applying my fix. When I add the resistor inline, I get 5k ohm...
Will try that! Thank you!!I didn't realize there are two level sensors in the tank.
You nailed it my friend, or at least I have had no check engine light for 500 miles!! I will post some pictures soon of how I did it with no permanent mods to any parts. Then put the panel back in place and wait for the other shoe to drop.
The sensor you tried to "fix" was likely fine.

There are 2 sensors, full and empty. When immersed in DEF the sensor will be low resistance (a short). When not immersed the sensor should be 10k ohm.

You might want to check the resistance across the other 2 wires. If it reads "open" then install a 10k ohm resistor across those wires.
I have had no check engine light for 25,000 miles :)
(at least none related to the Passive Tank or 4BCC code)
You nailed it my friend, or at least I have had no check engine light for 500 miles!!...
Here is how I did mine, somewhat of a step-by-step
1. Pull this panel off the bottom paying careful attention to how it overlaps or underlaps adjacent panels.


As mentioned, you will find passive tank under the drivers seat and to the left of the DPF. On the vertical surface of the rear of the tank, you will find the signal amplifier. Using a screwdriver, push catch to the side and push the amp upwards:


This gives you better access to both of the sensors wiring.

The catch to disconnect the sensors from the amp is where my screwdrive is. Gently pry that up and pull the gray plastic part out:


Press the gray plastic down to release the connector from the amp revealing the wires from each sensor. Black & Blue for the upper sensor and orange (red?) and yellow for the lower sensor. Ohm each pairs of wires to see which sensor has failed. My failed sensor was reading very sporadically.

I did not want to permanently modify the wiring (although it's a $60 harness) so I wanted to try something different. While testing, I broke a small cover off the male end of this connector, but that gave me an idea.
Bending the ends of the resistor wires like a fish hook, and coating them in dialectic grease, I stuffed the ends up into the faulty bays for the wires of the faulty harness and retested the ohms. After a successful reading, I stuffed the rest of the wire and the resister up into the connector.


Plugged it back in, cleared the codes using Carly and haven't had a problem for 500+ miles. Time will tell is my mod will hold, but so far I am pleased.

How many miles do you usually go before topping off the DEF because obviously the transfer pump will run since it believes the passive tank is always full?
Yea but what about a 335d sedan?
@jesus_man - Can you help clarify how in which pins you inserted the resistor? Did you use 1 or 2 resistors?
Here is how I did mine, somewhat of a step-by-step
1. Pull this panel off the bottom paying careful attention to how it overlaps or underlaps adjacent panels.


As mentioned, you will find passive tank under the drivers seat and to the left of the DPF. On the vertical surface of the rear of the tank, you will find the signal amplifier. Using a screwdriver, push catch to the side and push the amp upwards:


This gives you better access to both of the sensors wiring.

The catch to disconnect the sensors from the amp is where my screwdrive is. Gently pry that up and pull the gray plastic part out:


Press the gray plastic down to release the connector from the amp revealing the wires from each sensor. Black & Blue for the upper sensor and orange (red?) and yellow for the lower sensor. Ohm each pairs of wires to see which sensor has failed. My failed sensor was reading very sporadically.

I did not want to permanently modify the wiring (although it's a $60 harness) so I wanted to try something different. While testing, I broke a small cover off the male end of this connector, but that gave me an idea.
Bending the ends of the resistor wires like a fish hook, and coating them in dialectic grease, I stuffed the ends up into the faulty bays for the wires of the faulty harness and retested the ohms. After a successful reading, I stuffed the rest of the wire and the resister up into the connector.


Plugged it back in, cleared the codes using Carly and haven't had a problem for 500+ miles. Time will tell is my mod will hold, but so far I am pleased.

How many miles do you usually go before topping off the DEF because obviously the transfer pump will run since it believes the passive tank is always full?

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Zooming in on the picture, I put one resistor across pins 1 & 2 which correlate to the blue and black wires out of the back of the plug.



That was added in 2019 and I never had another problem. Just made sure to fill up passive tank every oil change.
Now that this thread has been bumped, I hope these details are useful.

The prior posts show how to access the wiring to the Passive Tank Sensors.
Resistance across the Black and Blue wires should be close to zero ohm when the tank is full, otherwise it should measure 10k.
Mine measured "open" so the resistor inside the tank had failed.

I soldered a 10k resistor between the black and blue wires.
The wires were cut and stripped, and a piece of shrink tubing was threaded on the wire (not shown) before soldering.

Finger Eyewear Cable Electrical wiring Electric blue


Shrink tubing:
Automotive tire Motor vehicle Automotive exterior Electrical wiring Cable


Wrapped with fabric tape, so it looks original
Automotive tire Hood Motor vehicle Bumper Automotive exterior



Resistance across the Brown and Yellow wires should be close to zero ohm when the tank is not-empty, empty it should measure 10k.
Mine measured 10k when empty, so I left it alone.

This was my favorite repair on the X5: took less than an hour, and cost zero (I already had all tools and materials needed).
No other issues with the Passive Tank for 5 years and 50k miles, until I sold the X5.
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