# Have you had an early DEF warning?



## Peda330i (Oct 26, 2005)

Got DEF warning at 5600 miles..figured I'd drive it for a while and take it to the dealer once I have around 200mi left. The warning every time you start the car is getting annoying though.


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## KarlB (Nov 21, 2004)

made it to my 13k mile service with no low def warning ever being triggered. was told def tanks were flushed and filled but dont have anything other than verbal on that-- the service did take about 3 hours though.


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## BR328 (Apr 9, 2007)

My thread on the topic

http://www.bimmerfest.com/forums/showthread.php?t=482920&highlight=


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## Philm35 (Aug 19, 2010)

Is there a document someplace that describes our DEF system's design/operation in detail?


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## clarkgd (Oct 15, 2010)

*Low Mileage DEF Warning*

My occurrance happened at 9300 KM when the No Start in 1600KMs came on. Initial diagnosis was that Active Tank was low and Passive tank was 100%. The active tank was filled under warranty and appointment made to diagnose the problem. At the next appointment the dealer tech spent 5 hrs conducting testing on pump according to toubleshooting procedures. Pump would run for 30 secs and then shut down. Pump replaced with same result. Found problem to be crystallized blockage of vent tube. Blockage cleared and pump ran to fill active tank.
Technician is not a believer in the troubleshooting procedure any longer. 
I don't know where this vent tube comes from or goes too but I suspect it likely links the two tanks and if blocked then the pump will not pump up to pressurize the active tank. Without the pump no refill of the active tank. 
Seems to definately be a design issue that these smart German engineers should be able to solve and as a result is a warrenty item and each case needs to be fixed and DEF added at BMW expense. Without the blockage, I would have easily had enough DEF to last to the first yearly oil change at double the mileage when I got the warning based on individual tank capacities mentioned elsewhere on the board.
:thumbup:


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## Snipe656 (Oct 22, 2009)

taibanl said:


> If so please add your name/mileage of the occurence/diagnoisis/corrective action/and whether it was covered to this list (and any other details). I am planning on drafting a letter to BMW NA
> 
> Edit: unable to add poll.
> 
> PLEASE REMAIN ON TOPIC


Name: Aaron Rouse
Mileage: Somewhere around 12,300, had it taken care of at 12,837. So somewhere around 6k miles past the first oil change. I know that my tanks were completely drained and topped off with my first oil change because I was there for that one.
Correct action: Dealer claimed they found nothing wrong and that it just sometimes happens. It was covered in the sense that it was time for my second yearly oil change even though the car was far from the mileage based oil change. Dealer said the fluid is only covered by BMW during an oil change.


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## autoJeff (Oct 1, 2009)

Late to the party...Taibanl PM'd me in March to respond in this thread but I've been away from the forums for a while...

I've twice run out of DEF prior to CBS oil change. I'd have to go through my records for mileage etc., but IIRC both times I was a couple months prior to a CBS oil change. I really was low on DEF. My issue was not inability to transfer fluid from passive tank to active tank.

Both times my dealer filled the tanks at no charge to me. The dealer ate the cost as an optional service to the customer; BMWNA doesn't pay for this. My dealer understood even before the SIB that a drain-n-refill is not required in this situation. I think my dealer saw it as a training opportunity, which can be worth more than a few dollars for the fluid. There were three mechanics around my car participating or helping with the refill. I believe the early adopters who were quoted a couple hundred dollars by their dealer for a top off were told that because at the time their dealer did not understand this and was looking to charge for a drain-n-refill.

I've read that DEF consumption is primarily a function of fuel economy. As fuel consumption increases so does DEF consumption (I think linearly). My car is a daily driver + family road trip vehicle. My typical mileage is 28-31 mpg around town with a long enough commute for the coolant temp to get to normal operating range. I assume oil temp too but I have no way to see the oil temp. On the occasional road trip I will average 36-40 mpg from driveway to driveway. In addition, my car has been to the track where I'll average below 15 mpg.

I've also read that DEF consumption rate is affected by a correction factor. The computer predicts the NOx level at a sensor downstream of the SCR catalytic converter. The difference between predicted and measured value drives the correction factor. Both short term and long term adaptation occur. This same system is the mechanism by which improper or ineffective DEF fluid is detected (i.e., don't "piss in the tank" as some on this forum like to joke.)

I got the impression that fuel quality can affect the correction factor. I wonder if diesel fuel in my region is not as high quality as in other regions, and if that's true then maybe it contributes to an increased DEF consumption rate. The next time my car is at the dealer I'd like to ask them to look up in the diagnostic computer the correction factor value for DEF use. If others can do the same then maybe we can compare by region and look for correlation with DEF consumption or particulates on the rear end. (I think several cars in my region experience particulates on the rear end as has been discussed in this forum.)

By the way, paraphrasing some material I have in paper format (no URL), the technical term for DEF is AUS32. It is a urea/water solution that is 32.5% urea. AdBlue is a registered trademark for AUS32, held by the German Association of the Automobile Industry. However, AdBlue is not the only producer of AUS32. There's a reference to a specification named DIN 70070.

The freezing temp of DEF is -11 C (12 F). The small active tank is heated. The passive tank is not. The line between the active tank and the SCR is heated. I suppose if you drive only short trips in a below-freezing climate then it might be possible to drain the active tank faster than fluid flows from the passive tank if the passive tank is not thawed long enough to fill the active tank. But I think you get up to 1000 miles out of a full active tank.


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## DnA Diesel (Jul 31, 2010)

I got the warning last week with about 2700km to go until servicing. I just did a quick fill of the active tank with the 1.89L bottle and good to go. I got the bottle for $27 a while ago, and modified the top to be able to refill it at the truck stops for $8.

Cheers
D.


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## Philm35 (Aug 19, 2010)

Thanks for your post, autoJeff. Some very useful information!


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## rmorin49 (Jan 7, 2007)

satmgr said:


> My Dealer did not know how to fill the upper passive tank (my sales person asked me how it was done) They would only fill the lower tank and as a result I got the low level alert after about 3000 miles? I've already notified BMW USA about the incidents. They did not respond to the event but I believe they probably sent out additional documentation to the dealers to take corrective action. I went to VW dealer and bought 2 jugs @2.5 gallons of DEF for less than $40.00, cut down the welded neck of a BMW bottle and loaded up the upper tank. The DEF is chemically the same but isn't shipped from Germany so its much cheaper to use. Just use eye protection and do it outdoors. Its a mild irritant so some of us would need to use rubber gloves and a clean funnel for transferring from VW jug to BMW fill bottle.


Can I buy a BMW fill bottle? What is the cost?

Sent from my iPhone using BimmerApp


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## Snipe656 (Oct 22, 2009)

rmorin49 said:


> Can I buy a BMW fill bottle? What is the cost?
> 
> Sent from my iPhone using BimmerApp


There is, I do not know the cost but also have read you can buy the VW fill bottles and they have the right outlet on them for our cars. Same fluid and tends to be cheaper at VW than BMW.


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## DnA Diesel (Jul 31, 2010)

rmorin49, the 1.89L Kruse bottle is $27 in Canada, so I'm thinking it's got to be $22-25 in America. The bottle has a one-way screw cap, but a quick trim with a box cutter and you can unscrew the cap and refill with cheap DEF from places like the Flying J or other diesel malls.

Cheers
D.


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## elester12 (Sep 2, 2005)

My 335d threw a fault code and triggered the check engine light. I've had an on going issue where the code comes back due to urea crusting up and the pump not being able to transfer the urea. I've stopped taking it to the dealer and just clean the parts myself.

I can't seem to get more than 5k before that message pop's up along with the fault.


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## Snipe656 (Oct 22, 2009)

elester12 said:


> My 335d threw a fault code and triggered the check engine light. I've had an on going issue where the code comes back due to urea crusting up and the pump not being able to transfer the urea. I've stopped taking it to the dealer and just clean the parts myself.
> 
> I can't seem to get more than 5k before that message pop's up along with the fault.


What are the steps you take to clean things?


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## elester12 (Sep 2, 2005)

I remove the hoses on the transfer pump and clean them out. I also clean the pump itself. 

When I removed the hose I activated the transfer pump and noticed the fluid was not flowing. After I clean out the pump and the hose I reactivated the pump and fluid was flowing. Normally the crust will build right on the outlet of the pump itself. 

I'm going to be in Germany over the next few weeks but I'll be happy to take pictures and write a DIY when i get back.


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## rmorin49 (Jan 7, 2007)

Snipe656 said:


> There is, I do not know the cost but also have read you can buy the VW fill bottles and they have the right outlet on them for our cars. Same fluid and tends to be cheaper at VW than BMW.


Thanks, I'll check this out as I plan to buy some DEF from a local Pilot Truck Stop. Does the VW bottle come filled with DEF?

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## elester12 (Sep 2, 2005)

It comes filled with Urea however the bottles VW sell's only has a small quantity. I would go to NAPA and get the 2.5gal. It comes with the adapter you need. 

Those bottles VW sell's are intended for a quick top off.


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## Snipe656 (Oct 22, 2009)

elester12 said:


> It comes filled with Urea however the bottles VW sell's only has a small quantity. I would go to NAPA and get the 2.5gal. It comes with the adapter you need.
> 
> Those bottles VW sell's are intended for a quick top off.


I thought VW like BMW sold different sized bottles. Since most of us are still under warranty periods then I'd think quick top off sized bottles are actually perfect. I'd get just one though then buy the larger containers from the parts store and siphon into the smaller. At least that is what I'd do if I had worries of needing some when on the road. Stuff has a limited shelf life so unless I had another vehicle that used it then I'd not stockpile up on it.


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## elester12 (Sep 2, 2005)

You're right. My x5 took an entire 2.5 gal's to top off after 3k miles.


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## Snipe656 (Oct 22, 2009)

elester12 said:


> You're right. My x5 took an entire 2.5 gal's to top off after 3k miles.


If my car triggered a low light just 3k miles after a top off then it would be going to the dealer for a problem. If I could not get there before it ran out then I'd top it off some to make it there or just tow the junk there. Alternatively I'd load it on our trailer and dump the stupid thing through the glass to their showroom floor. The last thought to enter my head would be to top off both tanks myself unless of course I was out of warranty.


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