35D DEF Tank Level Sensor Issue
 

2011 35D with 98K miles, 3rd party extended warranty. Engine warning light comes on and we take it in. After 5 days (including weekend) the diagnosis is the DEF tank level sensor is bad. Part in Germany. 1-2 weeks. $1,800 with a 20% discount for good customer. Says we can't drive it because the engine may shut down at anytime if it doesn't sense the DEF.

Well 5 weeks later, still no part. SA claims BMW holding up diesel parts or anything to do with diesel repairs due to the clamor over the VW diesel emissions issue. I find this hard to believe, but we are still out of our car which will be paid off next month.

They gave us a 2016 X3 3.5 with 23 miles on it as a loaner. Now has 2,340 miles on it. We are allowed 100 miles a day. Told us to keep it until the repair is complete. Nice SAV. Very quick. Love the exhaust note at shift under hard acceleration!

The DEF tank delay/backlog did exist before Dieselgate broke, but there have been reports also from before dieselgate that the DEF tanks were being delivered.

Seems these DEF tanks are starting to have a lot of problems and they are not cheap and do not appear to be easy to access/install.

Temp and level sensors, not sure if they are one in the same?

Not sure I would be standing in line for a Diesel anything. I have stayed away from them for this long, why take on these headaches now?

Both OPie and I have diesels. I have had diesel automobiles since 2000, two VWs and now BMW

I assume that BMW does not have enough inventory for these DEF tanks because they are failing at a much higher rate than they expected AND/OR they may be redesigning some of the sensors do to the high failure rate.

So it appears these tanks have temperature sensors, level sensors and a heater from what I gather.

Here is a picture of the tank with some of the senors.

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

I have passed on Diesels for my vehicles and I am not no hurry to get in line.

These diesels have their downsides, but honestly, I will take it anyday over the N62 and N63. N52 and N55 seems to fare much better.
My diesel has faulty DEF transfer pump, but instead of spending $400 i just keep adding DEF to the active tank every 2-3 k miles.
I visited a shop yesterday that are fixing '12 X5D with a broken active tank. I have to take a better look at it and take some pictures.

Ah, now I see, there are actually 2 tanks!!! Both not cheap and I assume both not so easy to access?

Would be interesting to see what tanks are having more problems.

I assume the OP is waiting on the Active DEF tank? Seems like more DEF tank problems are likely to start popping up in the near future.

I think everyone needs to be clear on what tank they are having problems with.

Oh what fun!

Passive tank failures are very rare. There is only 1 sensor inside.
Once we find a solution for adding external active tank temp sensor replace rate will go down 60-70% from whom is interested in DIY. Level sensor failures, like OPs, are much rare. But there must be a way to emulate this signal.
Last resort would be to disable the DEF in DDE(VW did it in a corporate level :stickpoke) or disable the DEF related codes. These solution will come soon as more and more diesels are going out of warranty and there will be a real demand. In the same way as replacing the dreaded N62 coolant transfer pipe was $6-8k years ago and now is offered for under a grand in many places.

I proactively installed a Bimmer Fix | Coolant Pipe Repair System coolant sleeve in my N62 when I replaced the water pump a few weeks ago for $200.

So hopefully I will not have to deal with a leaking coolant transfer pipe in my N62 during my ownership!

But there seems like a market will quickly pop up for DEF tank solutions.

Is there a transfer pump between the passive and active tank? I did not see one listed, but I did not spend a lot of time looking at the system since I do not have a Diesel. But I was just curious as to what/how the temp sensor functions and if there was a work around other than replacing the entire tank at great expense.

Wondering how much they charge? Here is another company fixing bmw def tanks for fixed 499.

So there is a market/problem with these tanks if people are offering repair service. The only problem with the one link is the fact you cannot purchase an outright exchange tank, so you must have the car down/apart while the tank is out unless the tank can easily be removed and the vehicle can still be driven.

One more problem system to live with!!!

It is a body shop and they have X5 with active tank that is broken from an accident. I want to take a look inside and take some pics.

Or go VW way :D
There is a transfer pump on the top of the active tank. The tank on the links is sold without the pump. Broken pump doesnt trigger CEL, but when there is DEF left for ~1000 miles the car will send you message-"No start in 995 miles" :stickpoke
We are exchanging some ideas for external sensor in another thread here. AT the end of the day the level sensor could be emulated too.

Don't forget to take a meter with you and measure the temp sensor resistance.:thumbup:

I would appreciate an explanation how the active and passive DEF tanks work. Which one gets filled when needed? Do either of them need to be drained prior to re-fill? Just curious.

Yea, aware of the other thread, I have commented on that too.

I wonder what would happen if a fixed resistance was inserted for the level sensor if this would trigger any other problems?

Is this like coolant or windshield washer fluid where you can physically see how full you fill the tank?

Active tank is small and heated when needed to prevent freezing. Passive tank is larger and passively heated by adjacent components. When the active tank level is low, DEF is transfer pumped from the passive tank to the active tank.

Neither needs to be drained prior to fill. That was an early BMW protocol, perhaps until it was realized how soluble urea is in water.

My intention is to not fill the active tank, to fill the passive tank only.

There is no way to see how full the active tank is. My guess is that it is a "fuel reserve" type of sensor that tells you when the fluid gets below a certain level.

And... mine failed (passive tank level sensor). When the tank is full I get no CEL. When the tank is low I get a CEL.

Member PIXLFIX over on Bimmerfest repaired their failed active tank level sensor by adding resistance between the two leads of the sensor. I will likely do the same if I can't find a cheap secondhand tank or sensor to swap in.

Can you post a link to the discussion?

Thanks. More info coming in ;)

http://www.xoutpost.com/bmw-sav-foru...blue-code.html

The fun starts at page #2

If they are replacing it, can you take the old tank? It would be cool to have a broken tank to do the external temp sensor idea and install it to see if it works.
Someone needs to be the leader in this and do the sensor :) I wish i was electrically capable cuz i'd do it. I can do mechanical things but none of that resistors and tricking the system stuff :/

Here is a OEM active tank wiring harness that can be used maybe?

I'll try to get the tank, but they may try to repair and reuse it.

Here is an article that talks about the DEF System and how it works.

Had an interesting DEF issue arise yesterday. Out of the blue got an 'incorrect fluid' warning, with 200 miles to no-start, and a 'check engine' light. Naturally, I was well over 200 miles from home or a BMW dealer in the middle of the Sierra Nevadas. The car has not been in for service for almost a year, in fact it is due for one; I topped off the DEF thinking it may just be low, but the countdown persisted for another ~75 miles, then disappeared. 'Check engine' light is still on.

In our 11 35d we've had both tanks replaced in the last 6 months. Active and passive, as well as just now the HPFP threw a code so they replaced that. Luckily under warranty still until May 2016! SA told me that they're getting close to extending the warranty on all the diesel emissions related stuff. Now that the VW fiasco has come to fruition, they expect BMW to be on top of this big time now. The EPA will wreak havoc if another one of these manufacturers has recurring diesel emissions issues.

Also, I have a friend/client here in Denver who's successfully been involved in several manufacturer class action lawsuits, on the plaintiff (our) side. He told me I'd need two more guys (to make it a class) and they'd be all over BMW NA in a heart beat. These are the guys who were part of the Firestone tire case, the Toyota gas pedal case, the air bag case(s) etc. Big litigation firm who thrives on this stuff and does a lot to keep these companies honest. Believe it or not, most really try to cheat the EPA guidelines and think if just a small % of owners have an issue, it's easier to deal them as needed and hope they go away.

^ Heck, you can get more than 2 people just from this board. Sign me up lol
Whats the info, any links? I would love to have this covered by BMW if i can. Cant even pass stupid inspection cuz this light keeps poping up for me after i clear it.

My car is on its fourth active tank, first failure was under previous owner. I had it replaced twice under parts/labor warranty, it seems to last just under two years. A tank costs 800+ and not sure where the other 1200 come from, the OP quotes 2k? Each time car is in for two days to get it fixed. I can't believe there is a wait of several weeks involved....

I happened to be at my local BMW Dealer Parts Department today picking up an online order. The parts guys are VERY good at this facility and I have been dealing with them for a number of years.

I happened to make some comments about the DEF tank issues and I was speculating that there may even be a Warranty Extension on these at some point. One of the guys mentioned some of the tanks are on "National Back Order" at this point. He was even shaking his head with no idea on delivery time frame.

I also think the $1200 in question is about 1/4 to make up list parts price and the rest is labor as I think this tank is not quick to replace.

This means a few things to me:

A. The failure rate is higher than expected and there is not sufficient projected spare parts inventory to keep up with the failures/demand.

B. The failure rate is higher than expected and the failures are being addressed with a revision or redesign delaying current availability.

C. The failure rate is higher than expected and the supplier is unable to keep up with assemblies for both new builds and field/in service repairs.

D. Everyone is generally screwed because the failures are on the uphill side and they will continue to snowball as these vehicles continue to age.

E. The critical mass of failures is not quite high enough to have 3rd parties come up with a cost effective solution with repaired cores available for purchase and exchange.

F. As much as BMW would like to come up with some overall software improvement to make this less of a customer annoyance, I think the VW debacle just killed any hope or idea of this ever happening.

I just do not see this story ending well anytime in the near future.

Good luck to all Diesel owners and their DEF systems.

We are good, no worries here ;) Even better with the patch for the temp sensor coming.
From what I read here the failures at colder climates are much higher, probably related to the fluid in the tanks freezing at some point.
Replacement of the active tank is actually not a big deal. A few bolts have to be removed, a few rivets and a few clips popped out to remove the bumper. Once the bumper is out there are 2 screws, few electrical connectors and a few quick disconnect hoses. I need to check the exact work hours in the KSD, but shouldnt be much.

Are you working on this patch? ;) :stickpoke

A patch/hack/mod may be helpful, however, at the end of the day BMW clearly has problems with the reliably of the DEF system and BMW really needs to step up and address this issue.

Amen to that, maybe we should let the EPA know. They may be interested in this, now that VW is in trouble BMW may act quickly :)
Anyone know the procedure to report such thing? I looked into it yesterday but didnt really see anything helpful on their site.

"Use this page to report what appears to you as a possible violation of environmental laws and regulations. Information you submit will be forwarded to EPA environmental enforcement personnel or to the appropriate regulatory authority."

Report Environmental Violations | Enforcement | US EPA

I have one question of curiosity because I do not and will not likely have a Diesel anytime in the near future. I see people say you can get a message like 500 miles to "No Start". Does this mean if the DEF tank runs low, OR there is some level related error that the engine will not start and is locked out due to a lack of DEF?

If this is the case I could clearly see how people would be concerned and upset with the entire DEF system in these cars.

I also wonder if Mercedes or other manufacturers are having similar high rates of failures in the DEF systems or if this is mainly a BMW thing?

Just not a lot of Diesels in my area and I am just trying to understand what the down side of a failed DEF system can be other than increased NOX emissions from the vehicle.

Never experienced it myself but i read that if it runs out of DEF or thinks that it has run out, the car will not start because running it w/o the DEF would pollute the environment so they programmed it to not start w/o DEF. That could be a headache if it senses no DEF on the tanks :x

I just sent some info to EPA about this issue, hopefully someone looks into it.

It can happen to any car to not start and it usually happens without warning. In my mind warning "xxx miles to no start" is a very comforting piece of mind.

I have a real problem with the fact that the DEF being low or having a erroneous warning can cause the car not to start. I assume this is the case due to the warning?

I realize there are a number of other situations that could cause a no start situation like running out of fuel, running your battery down or any of a number of other failures, but come on, DEF being low is going to leave you stranded. Just one more reliability problem.

I would love to read the EPA requirements that dictates that the vehicle needs to be disabled until the DEF tank is filled. If this is stated, the government again looking out of the consumers best interest, NOT!

With the high failure rate of the sensors in these tanks and the high tank cost due to the sensors not to being serviceable, I can see many people looking for a work around that in the end will probably cause these vehicles to put out excessive emissions. Not going to be a pretty long term situation for BMW or other manufacturers that have these high failure rates.

I mean one of the members is in need of the 3rd replacement tank?? Not very encouraging.

That is basically what i said in the EPA report i sent few minutes ago. Said people are and will be finding a work around and in long term, cause more damage to the environment and human health, sort of like VW has been doing.

ALL vehicles with DEF are disabled on empty. The BMW will run empty but not restart.

It is a 1000 miles warning. if you cannot fix the problem within this interval, the DEF is not your real problem in life ;) Pretty much every gas station now sells it and every truck stop has it.

Except when the warming is false because the level sensor is bad!!!

It seems this is one of the failure modes of the system.

If my fuel gauge fails, I can monitor my fuel usage using the Trip Odometer and drive for months without running out of fuel. Does not sound like this is the case with DEF level.

So you can run out of DEF and be a polluter, but you cannot restart the vehicle. Sounds like a rather STUPID process.

I personally would be disabling this feature very quickly even if the system worked properly and I would never run low on DEF.

There is no reason to disable the vehicle due to no DEF in my opinion.

More Nannygate and big brother that I do not need.

I can just think how many times my wife has run her car on fumes then told me I was elected to drive to the gas station to fill up her car. It is fine for me to walk, just not her!!!! :rolleyes:

The last thing I will add is that the system is smart enough to sense the exhaust quality and know when there is actual DEF is sprayed. Level sensor failure does not necessarily disable the vehicle, even less so immediately. If this function is not required by law no one will bother to pour DEF. If the catalytic converters are not required by the law most will remove them or never replace them when they stop working. This is the human nature.

So you must be fine with VW's recently publicized actions.

Whether you keep driving without DEF (in a car so equipped) or install a software cheat in a non-DEF VW, either way you are emitting NOx levels above federally mandated limits, which are there for a good reason.

Ever been to a heavily populated country that does not have emissions controls?

No, not fine with VW's actions what so ever. They cheated and got caught, but it also shows you how lazy the EPA is that they had to rely on West VA University to actually put a test system in the trunk and probe the tailpipe.

Here is the problem I have, screw BMW or whomever configured the car to not start if there is not enough DEF in the tank. Let's make somewhat of a parallel, if you are driving a gasoline vehicle that has a O2 sensors that is not working and/or a catalytic converter that is inefficient, the car is not programmed to not start. An indicator comes on the dash and alerts the driver to a problems. The exact same thing can be configured when the DEF tank is empty. Once the tank is empty the mileage warnings stop and a yellow indicator/warning comes on. Then it is up to the operator to take action to remedy the situation. The vehicle would not be eligible for Emission Testing, but this assumes the Diesels are even tested for Emissions, which in many locations are exempt. Diesels should not be exempt from Emission testing IMHO.

The cars are currently booby trapped to leave someone stranded and this is BS. I am not one to remove and bypass emission systems, but I would clearly bypass the no start situation in a heartbeat. Not to operate the vehicle without DEF, but to be able to operate the car without DEF if necessary. Whether is be the DEF tank is empty for some reason or there is a failure in the DEF system.

Yes, I lived in LA for a while!!

eeeh, like....China?

Pollution controls are necessary but to disable a vehicle is nonsense. Once these cars fall into the hands of the "last" owners there'll plenty of people working around that feature.

It is what it is, I've accepted the risk and learn to live with it. Praemonitus praemunitus.
One can be disabled with a flat tire on Pikes peak or overheated engine at Mojave with no warning at all.

Well said! Forewarned is forearmed. Good people ought to be armed as they will, with wits and guns and The Truth.

So some people passed around my email to the EPA, i was CCed in the emails and Mr Ross got back to me saying
"I looked further into the DEF tank issue and have found that BMW plans to replace defective tanks with a more robust version. You should check with your dealer to find out if you are covered by this plan."

He said he doesn't know timeliness but said ask couple dealers.

Yea, this issue is likely just warming up. The DEF system is part of the Diesel Emission system and I believe there are FAR to many premature failures.

I am sure there is more to come.

Can people ask their dealers as they go in for services so we get to hear from bunch of different dealers as to whats coming down the pipe, if anything?

It would be great if they issued a recall and didnt put 100k miles as the cut off for these tanks. I'd like to get mine fixed versus going the downpipe/tune rout for financial reasons.

My Active tank has a failed temp sensor too. Originally a NJ car but moved down to TX last year and my CEL came on after few weeks. Could have been covered by the Emission warranty 7yr/70K miles. Never paid too much attention to it. Fast forward to last month, dealer told me to SCR active tank temp sensor is bad and gave me $1800 estimate.

Called BMWNA if somehow they can help me, they said no.

Email sent to EPA.... We'll see...

Its one thing to give you a $1800 estimate, however, did anyone tell you how long the repair would take??

From my last understanding the tanks were on National Back Order and it was unclear when they would become available.

Seems the entire DEF system is a bit fragile and they are overall having failures at a very high rate.

Is there a mandatory emission testing in Texas?

Driving around a year or there abouts with the CEL?


EPA will do nothing.

Save your receipts- if BMW recalls the parts later you MIGHT get reimbursed.

Just had my passive tank replaced under warranty and picked up the vehicle this weekend. Actually looks like both the active and passive tanks are relatively easy to access. Active is right behind the front bumper on the passenger side which means bumper removal which isn't too bad. As for the passive tank, there's an under panel cover that covers it aside from that it looks relatively accessible.

Accessing the tanks isnt the problem, getting replacements and the cost of them is the problem. The bigger problem is the stupid integration of the sensor into the tank, nice job BMW engineers :rolleyes:

I overfilled both my tanks couple moths ago and been getting codes for both tanks. Im assuming now that the level went down, the codes havent been back. So im gonna say dont overfill the tanks and see if that gets rid of the codes (for those who have codes on )

Reminds me of the sulev fuel tank issues on the E46 models. You would think BMW engineers would have thought non serviceable tanks that contain sensors would lead to issues down the road, clearly they still haven't learned.

They clearly DO know it is an issue...State of Californina requires them to give and extended warranty to key parts costing over a certain amount- and BMW therefore lists the tank.

They know it is an issue.

Do they care about replacement cost to the public and second owners past 50k? not so much

BMW clearly is aware of the issue NOW as sulev tanks after the E46 were indeed serviceable. My point is that they obviously had to have felt the pain warranting all the tanks for the E46 platform so you would think designing a non-serviceable tank of any sort would be a thing of the past, clearly not the case.

As for the CA emissions warranty, my understanding is that it has nothing to do with the cost of the parts but rather their relation to reducing emissions. For instance the M56 valve cover, radiator, oxygen sensors, converters, etc were all covered under the 15yr/150k emissions warranty for the E46 sulev regardless of their cost. Also, the warranty was tied to the car, so no matter how many owners the car previously had emissions related parts were covered.

There are more parts that impact emissions than is in that list. However, I agree it may not be cost (the federal warranty does use cost, not sure on CA). It may have to do with expected failure rates? Dunno

For sure. Those were just the common parts. Thankfully I had my fuel tank replaced at 148k otherwise the bill would be $6k just for the parts!

You're right, I called them up again and confirmed they dont have the tank in stock.


Not sure.


Yes, it was on and off the first few months so I never really paid too much attention to it. Plus there were more important things that got in the way.

My last resort of course will be to replace it myself.

The other day I just got my check engine light with it being the DEF level sensor being bad. Also something about a secondary water pump not working, I wonder if that's the active to passive tank pump?

Either way, car is headed to the dealership next week. I just have to hope either they have finally extended coverage on this repair (my X5 is a 2011 with 72k miles) or that my 3rd party warranty will cover it. It specifically says it doesn't cover exhaust components, so who knows.

The secondary water pump is NOT the active to passive tank pump.

The DEF sensor is unrelated to the exhaust. Make sure you discuss this with the SA and make sure they understand how to submit it to your insurance. The word 'exhaust' should not be used anywere when they talk to your 3rd party.

I got a check engine light so I took my 2012 X5D to dealership, it was warning too much oil. they took my X5 in and checked the motor oil sensor is bad, they also took me that my active DEF tank is bad. this is my second active DEF tank being bad......I am still under warranty, so it was free for now......

Got it, thanks!

Also I don't know if I should be more worried or relieved, but my check engine light was gone this morning. :stickpoke

I was getting a sporadic CEL, for active tank temperature sensor code, and asked the dealer to replace the tank under the 7 year/100k mile extended warranty. I believe walking in knowing already knowing the specific code, the integrated sensor/tank replacement issue, and emissions section of the warranty, all made a significant difference - thanks to this forum. The US $50 deductible was the least I've ever spent at a BMW dealer!

The people saying they've been getting DEF tanks replaced under warranty, are you guys talking about the 4yr/50k or the 7yr/70k emissions warranty?

I'm still under 7yr/70k but outside of the 4yr/50k.

Cool location.... what is the warranty in your ess?

Tank is covered under 4/50; extended 6/100 (cpo or bmw) and under the California 7/70. it is NOT covered under the federal warranty

Well, word just came in, my piece of crap aftermarket warranty is NOT covering the DEF repair. This thing was the biggest waste of money ever. I'm glad I only bought the two year and didn't spend an extra grand on the three-year.

So now I have to decide what to do. I'm not going to pay the dealer $1800 to fix it. In TX they do not do emissions checking on diesel vehicles, so I'm tempted to go the route of eliminating the system entirely and removing the DPF. However, I kind of hate how I'd be polluting a ton more due to that.

Or I spend $800 on the tank and try to install it myself.

Or I trade the car in (I've only had it a year, but I love it, and would rather not part with it) for an i3, since their lease deals are fantastic right now

why not buy a thermistor or resistor for $10 ?

I'll be going that route in the spring. Currently, when the CEL comes on I fill the tank and it turns off.

Why have I heard nothing of this before? Specs on resistor needed please?

If you're talking about a DEF tank level sensor, then this is the link to check out. Some refer to it as the PIXLFIX fix!

On the other hand, the DEF tanks can also have the temperature sensor go bad. Not sure there is an "official" fix yet, but this posting from the M57 turbo diesel forum looks really promising. Here is the link for a $4 NTC 10K thermistor. The work was done on a 335d rather than an e70 35d, but it should be very similar. The only thing I'm not sure of is whether the specs (10k ohms at 77 degrees F) match the original thermistor. Also not sure how the epoxy coating will hold up to urea.

Hope that helps.

Wow. Nice. Thanks so much

Thank you all for contributing to this post. We have a 2011 35d with 124,000 miles on it and have had several active tank issues and ended up paying to replace in the 85,000 range as our extended warranty did not cover. I am a long term (1988) BMW owner and we love the X but it has sure been the most troubled. Thank goodness for this forum and those that contribute technical advise!