'11 CEL AdBlue code
 

So my wifes '11 is 35D is in the shop right now for new front brakes. The CEL has been on for the last few weeks. They topped it off today and reset the code, afterwards it came back on (2x). The code they said they are pulling is the AdBlue sensor. They said if it happens again they are going to replace the sensor. I have searched the forums and not seen anything similar. Thoughts?
thanks

You should get the code and post it, is it saying you have this many miles to go before it runs out or is it the code for the temp sensor because they are different and one will be easy, other will put a sizable hole in your wallet. You cant change just the sensor on the urea tanks, the whole tan needs to be replaced.

Get the code, scan it yourself, take it to autozone for a free scan.

Waiting for the response from my wife regarding what exact code it's pulling...thanks. Hopefully they will give it to me otherwise i will go to autozone tonight.

I searched before regarding the codes for the adblue issue and did see the temp sensor come up a few times. I saw different prices and didn't really research the exact cost but did see some of the parts being in the $400 range. Is this correct? That plus labor makes me scared for a bill north of $550 for a bad sensor.

The dealer rate for passive and active tanks are around $1300 a piece, may be able to find it cheaper but they arent cheap. I have codes for both tanks at the moment and im NOT spending that much to fix them soo.. i may go with the DPF delete method and eliminate all that crap.

Appreciate the feedback

My wife just rolled up and was told me "They aren't sure which part I need. It's either a new ab fluid tank or the valve on the outside. Will show you a picture. later. Code is 46F9-P205C. He said "if you do your own research, don't believe everything you read.""BMW forum isn't always a good thing"

Kinda curious how they can't figure out why they can't figure out what's the root cause.

Is replacing the valve a good thing to try and fix first? Seems like it would be less expensive to start with. what kind of delete are you mentioning? Sorry not familiar. Appreciate the input.
Thanks again.

Ahahaha... THAT is very true; just like "BMW Certified Technician isn't always a good thing"

Read, learn, and draw your own conclusions: don't believe everything you read on forums and don't believe anything the service advisors tell you. The important things to know is that 6-Sigma and QA not only improved the repetitivity of process as a prerogative to quality; but also results in the repetitivity of issues: meaning 99.9% of the time you have an issue, someone else had it. Forums have a broader user base than your local dealership and allow to see the recurrance of issues.

Now, back to your issue.

That code has to do with the temperature sensor in the active tank. You can thank BMW and Bosch for having to replace the whole damn tank for a stupid temperature sensor. But yea, it happens quite often.

Replacement of the tank requires the removal of the front bumper and then it's right there. The price of the active tank has come down substantially and it's now around 900 bucks from the initial 1400. There's reconditioned unit for sale by a Canadian supplier that go for 450 but I doubt a BMW dealer would use it.
You can find the tank online for 20% for a net of 788.58 (BMW Parts and Accessories | GetBMWParts.com). If your dealer doesn't want to match that ask them the list of parts they need and you will supply it to them.

You're in FL: on one side you have very lax emission regulations, on the other you don't get CA Emission Warranty that may have covered you...

You can obviously continue to drive with your CEL on and forget about it.

^^^ Well said and well described!!

Do not know much about the Diesel, but what about spoofing the temp sensor circuit with a resistor of some sort??

Might be an idea, not sure if it can be pulled off, but might be worth considering.

The sensor is a negative coefficient temperature sensor which is pretty much how most coolant temperature sensor work.

If it was my car I'd try to drill the tank and add a regular sensor somewhere and then wire it into the loom.

I wouldn't just bypass it since it would take just as much effort...

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^ Thats an idea, as long as you match the wires up it should work sounds like.
Maybe someone with a bad tank will do it and report back.

You will have to find a urea specific sensor otherwise it would get corroded prematurely.

Something like this is a good stainless steel interface that can then accommodate a variety of sensors. Assume the tank is plastic? Not sure how thick, but I assume this could be epoxied into the tank, or a plastic block that was drilled and tapped could be epoxied to the tank and then this could be threaded in?

Seems like the main PITA would be the effort to access/remove the tank if needed.

Schneider at 225 4" inch Stainless Steel Temp Probe Sensor Bulb Well 1 4 1 2 NPT | eBay

Then you could slide one of these into the cavity. Fill the cavity partially with RVC and insert the sensor.

This assumes the sensor values are close, if not could be adjusted with a resistor. I assume the temp of the fluid is not ultra critical, probably determines how much is used, but a few degrees here or there is probably good enough?

Sounds like someone should consider a "kit" because it seems these are not uncommon problems.

Or this $43 one.Its negative temperature coefficient (NTC) thermistor with 20 kΩ NTC Thermistor.Not sure whats the spec of BMW.But i guess that values can be adjusted by using external resistors.

Stainless Steel Temperature Probe > Vernier Software & Technology

It may be worth looking through Rehingold see if anything comes up in terms of measurements.

Alternatively, again with Rheingold, you should be able to get a read of the sensor and do the temperature calibration that way if needed.

Sounds like you two know all this electrical lingo and should put a Urea Tank Fix kit together and we the electrically challenged ones will buy them to fix our diesels and stick it to the dealer :)
Assuming a regular DIY'er could do this job with some instructions.

If BMW uses a thermistor, you can probably figure out what size it is by measuring the sensor resistance with a meter. Typically, thermistors are rated at 25C (77F). I use 10k stainless sheathed NTC type 3 thermistors with and without wells.

I would be more than happy to supply one of these sensors if someone wants to give it a try.

I'm looking forward to seeing a fix it here.

That is great news to have someone who is familiar with these sensors.

Here's a few more info I was able to dig out.

Code 0046F9 is described as "Reducing-agent active-tank temperature sensor, signal"

The description is: "Sensor monitoring, active tank temperature sensor. The fault is set if the raw sensor signal (voltage) drops below the minimum limit value of 165 mV."

That would be great if someone with tank in hand can measure sensor resistance.Yes Bmw uses thermistor instead of thermocouple.

I tried to get info about active tank temp sensor with X5 hooked up with rheingold.It doesn't give resistance values instead gives voltage values.
eg. when the temp was 25 deg C,then sensor voltage was 1061mV.

My engine was still little warm that's why there was difference of 5 deg C.So in that way we can try using 10K,20K thermistors and can check which one gives temp value same as ambient temp.

Here is the screenshot.

If someone can provide the sensor and wiring diagram, i'd be willing to drill my active tank and bypass the OEM sensor since i have the temp code on at the moment and it doesnt go away :/

I think the tank doesnt have to be drilled. The computer will accept the temperature that is close to the ambient. With engine running the temp AROUND the tank will be a bit higher than ambient, as in the ISTA example.

So the sensor will go on the tank somewhere, doesnt have to make contact with the DEF fluid? What about for cold climates since im in NY. Will this still work?

Probably if it is attached to the container and there is some heatshielding over it it should be pretty accurate.

Ozer, if you can find the connector for the temp sensor in the tank, see how many wires it has. I would expect 2 wires, but it could be more.

Do you have software or a scan tool that can "read" the current temperature of the DEF tank?

Does the DEF tank error light the SES/CEL/MIL and does it provide Freeze Frame data that may have the tank temperature when the error occurred?

Basic thermistor sensors are usually pretty reliable, the problem is most likely with bad solder joints on the sensor itself or wiring connections at the connector.

I am not sure why the DEF temperature is important, I do know that the DEF will slush or freeze and maybe the temp sensor main purpose is to prohibit the DEF from being used when it gets close to slush temperature?

Maybe the temp is also used to precisely adjust the DEF amount as well, I have no idea.
I assume the ideal position for the sensor is in the bottom of the tank so it stays submerged in the DEF?

But a working sensor near the DEF tank may be helpful and work out.

My guess too. Perhaps someone with more knowledge on DEF systems may chime in, but I dont believe that a few degree inaccuracy of the fluid will have catastrophic consequences.

I will see if i can unplug it this weekend and see if anything is corroded with the harness. I only have couple apps, Carly and Fusion which has freeze frame but not sure if it shows DEF temp. I will check. I can see the code in pending status and after a while it throws the CEL.

It is because the temp sensor values are used by DDE to heat the DEF in active tank as there is a electric heater inside the active tank.

If you have a good multimeter, I would be curious to see what the sensors current resistance value is (I know it's "bad").

If only this is the function, placing the sensor outside with some heat shielding will do the job.
This may turn into a 10 minute job with $100s of savings ;)

Here is a link with some pictures of the DEF tanks.

https://www.ecstuning.com/ES254461/

https://www.ecstuning.com/Search/Sit...2146/ES254457/

Seems these stupid tanks are having a number of failures and there is an active and passive tank, each cost about the same amount, discounted around $800. Wonder it it is just one tank that has the higher failure rate?

Again, I am not an expert on these tanks but it appears they have a level sensor, a temperature sensor and a heater. These cost around $800 at a discount level and may not be so easy to access/replace.

The good news from the picture is it looks like the DEF tank is somewhat designed like a BMW gas tank with a large collar that can be unscrewed and the senors may be accessible without having to drill the tank. This assumes the collar can be removed without damage or breakage. So someone will have to be the guinea pig on this project. I would probably see if you could find a used tank for a decent price so you could open it up and come up with a solution so your car would not be apart and down while trying to come up with a solution of some sort.

Couple this with these tanks are NOT current readily available for some reason. I can only assume this is due to a high failure rate of these tanks AND/OR a possible redesign of some of the tank parts.

There is another person on the forum that the tanks are not currently available and back ordered for probably a few weeks, maybe more, for a tank from German!

There is obviously more to this situation and likely more failures to pop up in the near future.

I wonder when the letter from BMW will be coming out that is extending the warranty coverage on the DEF tanks? :D

A defective DEF system would cause the NOX emissions to probably be above acceptable values, would be interesting to see how BMW addresses this with VW Dieselgate problems.