# New owner of a '11 335D - got the DEF light - gut check



## Gpw76 (May 15, 2016)

Good evening,

I have put on 1,000 miles since purchasing my 2011 335D last Monday. The car has been wonderful to drive. Car has both the Premium and Sport packages, along with the HK/L7 sound system.

Upon going to work this morning, I was notified of the "999 miles to No Start" due to the DEF fluid being about gone. I have read about this (and other items) regarding the 335D before actually purchasing the car, so I had a heads up and already purchased a 1/2 gallon of DEF from a Audi/VW dealer to be prepared for this day. Its being patiently waiting in the trunk  .

So here is my line of thinking - a gut check of sorts ... Since I just received the notification, that means that the passive tank is empty (or just about), right? So I am thinking about getting the 2.5 gallon of DEF from the auto parts store and just fill up the passive with the (now) 3 gallons - doing the .5 gallon one first and use that as a make-shift funnel for the bigger container. Then let that cycle through the active and be on my way. 

While this may not fill up both tanks, thus requiring me to add DEF that much sooner - but I rather do that than take the risk of overflowing and ruining the SCR system.

Thoughts? Am I being too cautious? At this stage am I all clear to put in the 4.5 gallons into passive or just stick with the original 3? I guess that part is what I am unsure about.

Thanks!


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## montr (Oct 7, 2006)

Gpw76 said:


> Good evening,
> 
> I have put on 1,000 miles since purchasing my 2011 335D last Monday. The car has been wonderful to drive. Car has both the Premium and Sport packages, along with the HK/L7 sound system.
> 
> ...


That is exactly what I do now, put 2.5 gallons in passive tank when needed. I had a DEF tank failure when the car was serviced by the dealer, prior 50 K miles. Since I am refilling the DEF tank, from 50 K miles to 81 K miles, I did not get DEF tank failure or any related DEF codes.


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## FredoinSF (Nov 29, 2009)

Also what I do. 2.5 gallons in passive tank and let the pump do its job.


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## Doug Huffman (Apr 25, 2015)

+1


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## need4speed (May 26, 2006)

montr said:


> That is exactly what I do now, *put 2.5 gallons in passive tank when needed.* I had a DEF tank failure when the car was serviced by the dealer, prior 50 K miles. Since I am refilling the DEF tank, from 50 K miles to 81 K miles, I did not get DEF tank failure or any related DEF codes.


me too


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## MotoWPK (Oct 5, 2012)

Gpw76 said:


> Good evening,
> 
> I have put on 1,000 miles since purchasing my 2011 335D last Monday.
> ...
> ...


When the DEF 'miles to no start' warning appears, it is the active tank that has reached a low level, the passive tank already having been emptied replenishing the active tank.

There's certainly nothing wrong with adding DEF to the passive tank only, the system will then transfer DEF from the passive to the active tank, but this will mean you will need to add DEF again that much sooner.

Using the top of the 1/2 gallon container as a funnel will prevent you from overfilling the system as the shutoff valve in that container will close when liquid reaches it. Your also not at risk of pressurizing the tank since your only filling by gravity.


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## Gpw76 (May 15, 2016)

Thanks everyone for the insight.


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## Doug Huffman (Apr 25, 2015)

MotoWPK said:


> [ ... ]Using the top of the 1/2 gallon container as a funnel will prevent you from overfilling the system as the shutoff valve in that container will close when liquid reaches it. Your also not at risk of pressurizing the tank since your only filling by gravity.


When the fluid reaches the filler neck fitting the tank is over filled and the sintered air filters are wetted and in danger of clogging. That is why we above are speaking of a specific volume less than the capacity of the passive tank.

The half-gallon bottle that I used had no active shut-off, merely a spring loaded shut stop valve.



> *SI B 16 02 10 March 2010. Subject: Proper Diesel Exhaust Fluid Level in SCR Reservoirs [ ... ] RECOMMENDATION Do not overfill the SCR system. Filling the tanks to the top of their respective filler necks will cause the DEF to leak out of the tank's vent system, and will possibly damage the tanks and internal components. [ ... ]*


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## MotoWPK (Oct 5, 2012)

Doug Huffman said:


> When the fluid reaches the filler neck fitting the tank is over filled and the sintered air filters are wetted and in danger of clogging. That is why we above are speaking of a specific volume less than the capacity of the passive tank.
> 
> The half-gallon bottle that I used had no active shut-off, merely a spring loaded shut stop valve.


It would appear that the system is designed for filling to the top of the fill line since the manual states;

"Press the bottle down, see arrow.
The vehicle container will be filled.
The container is full when the fill level in
the bottle no longer changes. 
It is not possible to overfill."

ref: BMW X5 Owner's Manual, pg. 209

The level in the bottle will not longer change when the valve at the bottle discharge closes, which it will do when the DEF reaches the valve (which will be at the top of the fill line when filling from the bottle).

Consistent with this, the fill lines connect to the tanks at a lower level than the vent lines are connected.


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## Doug Huffman (Apr 25, 2015)

The owners manual also says


> Refilling quantity Refilling quantity at the start of the reserve display: Approx. 0.75 gallons/2.7 liters[my emphasis]


I note that my owners manual copyright date is 2011 and later than the SIB. BMW has a problem

As to the significance of the height of the fill lines on the tank relative to the vent, it is not significant. What force closes the bottle discharge valve, or opens it for that matter?


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## KeithS (Dec 30, 2001)

As others have said just put the 2.5 gallons into the passive when you get the low DEF indication. I have been diagnosing some issues with my DEF tanks and put just 1.5 gallons into the passive. Right after I could hear the transfer pump running when I parked the car. Soon after it was apparent the DEF was transferring. I believe the transfer only happens right after the car is shut off and not while in motion or the engine running.

At 80K miles I have the original DEF tanks. I have a bad high level sensor in the active tank, which is apparently common. Going to the dealer in a few weeks, car has the platinum extended warranty.


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## MotoWPK (Oct 5, 2012)

Doug Huffman said:


> ...What force closes the bottle discharge valve, or opens it for that matter?


When liquid in the fill line rises above the fill line vent, near the open end or fill port, liquid will stop flowing from the bottle since there is no longer an atmospheric vent available. When you twist and remove the fill bottle, the valve disc closes from gravity and the head of liquid above it (the liquid in the bottle).


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## montr (Oct 7, 2006)

MotoWPK said:


> When liquid in the fill line rises above the fill line vent, near the open end or fill port, liquid will stop flowing from the bottle since there is no longer an atmospheric vent available. When you twist and remove the fill bottle, the valve disc closes from gravity and the head of liquid above it (the liquid in the bottle).


You are maybe correct for the E70 35d.

However, the E90 335d has a second vent on top of the DEF tank called "operating vent". The vent next to the filler tube is closed when the filing port is closed. The second vent, on top of the DEF tank, is vented to the outside and is below the filling port vent. When someone fill the tank up to the top of the filling port, DEF fluid leak on the top of the DEF tank and may damage the DEF pump and sensors. All this info is in the Service Information Bulletin from BMW.

BTW, on this forum, if you search for picture of DEF tank that have been removed from a 335dd, you will often see DEF crystallization on top of the tank.

To me, it is not that important that the tank be filled to max capacity. I prefer to play safe. Also, it is good to remember that the DEF has a shelf life of 1 year.

In the picture below, you can see the operating vent is "4"


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## MotoWPK (Oct 5, 2012)

montr said:


> You are maybe correct for the E70 35d.


Actually, in my previous post, I was quoting the manual for my F15 (MY 2014), and perhaps that points to a design difference between the older and current series that partially explains why the reports of DEF tank failures appear to all (or almost all) come from owners of older series.

Hmmm...


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## MotoWPK (Oct 5, 2012)

Was reviewing info I have on this subject which includes;

SI B 16 02 10 March 2010 - which cautions "Filling the tanks to the top of their respective filler necks will cause the DEF to leak out of the tank's vent system, and will possibly damage the tanks and internal components."

SI B 16 02 10 June 2010 - which states "This Service Information bulletin supersedes SI B16 03 10 dated March 2010", though mostly covers the possibility of a low DEF warning prior to oil service being due. This document refers to SI B16 01 09 "to properly drain and/or refill the active and passive tanks".

SI B 16 01 09 March 2010 - "SUBJECT DEF Extraction and Refill" - Most of this document describes emptying the active and passive tanks using the 'DEF Extractor'. Interestingly, there are no specific instructions included for refilling the system except a listing of the E70 and E90 tank capacities and the note "Warranty will only reimburse the use of 2.5 gallon service bottles (P/N 83 19 0 440 158) when draining and refilling the SCR system.".

I have read somewhere on Bimmerfest or Bimmerpost that draining of the system was no longer required. Can anyone confirm this and have reference to a BMW document that so states?

If draining is still required, it is clearly something that is not being done by most, if not all, owners refilling the system themselves.

Also, if draining the system prior to refilling is still required, perhaps this answers a question as to how far the system is refilled; i.e. not to a level, but to a volume corresponding to the active and passive tank capacities. If that is true, I can't help but note the lack of specific instructions to that effect in the reference SIB's.


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## Gpw76 (May 15, 2016)

Just following up here. I did the 2.5 gallon service and everything went well. Thanks everyone for the information. But curious, how big is the passive tank?


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## KeithS (Dec 30, 2001)

I believe on the 335D the passive tank is 4.0 gallons.


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## diesel fan123 (Nov 25, 2011)

I'm curious about the "shelf life" of DEF. 
What is the chemical effect of age on DEF? 
The DEF in my 335d tank takes over a year before requiring a refill.
Other than crystal growth, what can go wrong with DEF?
Frank


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## Doug Huffman (Apr 25, 2015)

diesel fan123 said:


> I'm curious about the "shelf life" of DEF.
> What is the chemical effect of age on DEF?
> The DEF in my 335d tank takes over a year before requiring a refill.
> Other than crystal growth, what can go wrong with DEF?
> Frank


In ideal circumstances a shelf life of two years is cited, one year under typical storage conditions. Age has no effect on DEF. Crystals cannot grow in an isolated system.

Here is the patent http://www.google.com/patents/EP2551009A1

Here is the ISO 22241-4:2009 http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=42941


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## Flyingman (Sep 13, 2009)

6 1/2 years, 105k miles. I've never had an issue with the DEF itself.

The pump and tank (heater) yes.

If you ever spill any DEF it will quickly crystalize but kept sealed within it's own tank or container, it should be fine.


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