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Discussion Starter #1
Hi All,
Second post on a Bimmer board so hopefully I can avoid toes. Did a few searches both in Google and using the forum search. Didn't find much that fit my issue with the F30/31.

Had the car about 12 months. Drives well with the exception of stuttering on WOT (I'm assuming it is Transfer Case) but the issue I have recently developed is perplexing me.
I am going through DEF like crazy, from full to 1000 mile alert in around 2000 miles, plus the mpg has dropped from a regular 43/45 to barely being able to keep 36, all on a 400 mile highway runs (my commute is an 800 mile round trip). If I rag it, it drops into low 20's. When I first got the car it was nigh on impossible to drop into the mid 30's no matter how I drove.

Looking at winter mpg's on the forum doesn't seem to make up for the drop in mpg's nor the DEF...and the two may not be related.

Looking at different BMW engines people mention the thermostat as a potential issue or potentially the EGR.

Any ideas before I head to the dealer and grab my ankles? I'm a competent DIY mechanic bu new to BMW and new to diesel.

thanks in advance
 

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I'd start by purchasing a capable scan tool, or getting a USB dongle that's compatible with some of the software and / or mobile applications that can read BMW specific codes / chart live data from sensors & modules...

Anything from a sensor malfunction, to leaky intake air ducts / exhaust manifold, to failed emissions components, a dragging brake caliper, as well as a host of other things I'm likely forgetting could cause the symptoms you've described...

The hiccuping on hard throttle is likely related if I were to guess, and is also not likely a TC issue... However, I'm purely guessing, because I have nothing to go on, where I'd certainly not trust my guess to the point of putting any money on it...

Modern vehicles absolutely require a capable scan tool and / or software to properly diagnose issues. You will NOT get anywhere trying to fix / diagnose issues yourself unless you are able to grab BMW specific codes, and you'll likely not get many responses for issues you post without codes, or the ability to gather them.

Me personally, I went with the Foxwell 520 Pro w/ BMW software loaded on it. About $150 on Amazon; however, there are other less expensive options that can do basic functions of reading BMW specific codes. The ability to gather live data from sensors & modules is also pretty much essential as well if you're going to attempt diagnosis of issues.

With codes in hand & the ability to gather live data, I'd imagine there's someone on here, or elsewhere, who could assist with diagnosing the issue to at least the general system that should be examined / investigated. Without this data, it's anyone's guess & most will choose to not waste their time guessing.
 

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I would agree with @SPL15 that one of the code readers would be a wise investment as well as nearly essential to both finding the problem/getting advice on the issue, not to mention fixing the problem. I would agree that you have at least one, and maybe two.

That certainly is high DEF usage, and low mileage. Both could be something as simple as a leak, or a thermostat, although I don't think the latter could cause THAT much mileage/DEF trouble. The code readers recommended would show low coolant temperature even if that didn't set a code. Carly for BMW with it's dongle is around $100. Ditto Blue Driver, which is what I use.
 

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High DEF usage is uncommon. A least on the E90 models, DEF clogging is an issue but not the opposite. Is it possible that a) you are filling the passive tank but it is not refilling the active tank or b) you are only doing a partial refilll?
 

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High DEF usage is uncommon. A least on the E90 models, DEF clogging is an issue but not the opposite. Is it possible that a) you are filling the passive tank but it is not refilling the active tank or b) you are only doing a partial refilll?
Highly doubtful... If DEF was not reaching active tank, where SCR system would not have enough DEF, there'd be tangible symptoms of iDrive warning, an SES light, & possibly limp mode & a mileage countdown. Codes & a dire warning on the iDrive, in addition to limp mode would almost certainly be be the case due to apparent SCR efficiency due to the additional NOx.

Without codes, as I'd imagine there will be a few hidden ones, it's anyone's guess... I'd speculate an EGT sensor issue or a NOx sensor issue, or some sort of exhaust and / or EGR temp sensor issue, but it's purely a wild guess as it could be a variety of legit mechanical issues as well as other faulty sensor issues, as well as multiple issues at the same time... I'd also guess, with a fair amount of confidence, that the issue is likely something pretty easy to diagnose & fix in the driveway for a fraction of the cost of having the dealership diagnose & fix it, but it would require knowing codes & access to live data...

Get that code reader, ASAP! ;)
 

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I don't see anything suggesting what your odometer reads.
Look into "DEF Slip", and also hone in on poisoned NOX sensors/ cstalyst issue.
Do you have evidence of DEF deposits at the tailpipe?
Don't discount the possibility that you are dealing with a compound issue. Did you fill your own DEF?
 

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Discussion Starter #7
Error code U010E

Hi all,
thanks for the responses so far. I have a tool from scannet, ODB Whiz that I have hooked a laptop to. The only pending code is U010E and looking online it mentions checking the EGR and mentions that an RCM miscommunication may be incorrectly controlling the injection of DEF. The checks suggested are generic in terms of checking grounds etc.

Is this a code folks have encountered before in conjunction with EGR/DEF injection?

Any other thoughts welcomed.

Addressing other questions:
yes I fill own DEF and the quantities are right from filling to empty.
No real indication of pipe deposits or at least nothing out of the ordinary.
Mileage on vehicle is 88K

thanks again
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 100K miles NOKIAN WR G3 20K miles
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For what does RCM stand, please, R Control Module?
 

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Discussion Starter #9
here's the link my scantool sent me to. I have looked online and didn't find that much.
https://www.obd-codes.com/u010e

There is also a more specific code: EACM-ExhaustAftCtrl ($7EC)
but that specific code seems to show even fewer results.

It states the R is for redundant so RCM is Redundant Control Module. A more complete explanation is given in the link above.
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 100K miles NOKIAN WR G3 20K miles
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here's the link my scantool sent me to. I have looked online and didn't find that much.
https://www.obd-codes.com/u010e

There is also a more specific code: EACM-ExhaustAftCtrl ($7EC)
but that specific code seems to show even fewer results.

It states the R is for redundant so RCM is Redundant Control Module. A more complete explanation is given in the link above.
"The DDE control unit performs the following functions:

Evaluation of the nitrogen oxide sensors
Calculation of the injection rate of AdBlue and transmission to the SCR control unit via PT-CAN
Control over SCR system deactivation
The SCR control unit has to ensure that the input parameters for metering via the DDE are within the permitted range:[ ... ]"https://www.newtis.info/tisv2/a/en/...nents-with-a/a210-scr-control-unit/1VnXOE4L9R

Your mechanic is lying to you, the DDE controls your SCR injection.
 

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Discussion Starter #12
Agreed on the generic codes and no worries on the lying mechanic. The reference is not necessarily for a BMW - it is a generic web service that connects people to mechanics and the response is designed to be generic. Apologies for not being more explicit regarding the source of the information.

Not sure why the U010E code is so generic. I thought the ODBWHiz tool was good but I'm switching from Saabs to BMW and it may not be effective on the latter.


Sounds like either a trip to a dealer to get more on the code or invest in some BMW specific software.

Anyone know what "EACM-ExhaustAftCtrl ($7EC)" refers to?

thanks
 

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Have you checked your SCR control unit? It should be above the battery. Maybe your code is saying there's an issue with communication between the DDE and that. Here's the system description.

Item #1 in this diagram.


You'll probably want to download ISTA+. There are links around the forum in the coding section to download it and installation instructions (not super straight forward). That will give you the explicit BMW code meanings.
 

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This may indeed be one of those times you might need a dealer, at least for diagnosis if not for fix. Do be aware that at least some DEF/SCR systems in some BMWs have had warranties extended by BMW to 120,000 miles, so it is possible your issues are covered. I'd certainly ask if they don't bring it up.
 

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Discussion Starter #15
Hi all again, some follow up.
Used BimmerLink app after reading some of the recommendations from others in terms of how complete the code library is.
When I initially connected there were all sorts of codes in the memory for all sorts of things. After going through them there was nothing obvious. I cleared them and figured new ones would be of the greatest interest.
I've driven around 50 miles since the clear and the only particularly relevant motor based code is a 26CF00

26CF000 - fuel pre-supply pressure control, pre-supply pressure too low/positive control deviation. I'm not seeing anything on the RCM error returned by ODBWhiz.

The symptoms I have are low MPG and excessive use of DEF. I avoided the dealer when they said it was cost $160 to read a code and $460 to replace a wheel bearing. I did the wheel bearing (cost $100 all in and about an hour of time), but I'm beginning to think I may be more dependent on a diagnostic from them than I want.

Any suggestions on the code? Seems unrelated to the DEF/MPG issue. It also feel that the DEF/MPG issue is not dropping a code...or I've not driven far enough.

any final thoughts before I grab my ankles at the dealer?
 

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02/2012 X5 35d M57Y CPO 100K miles NOKIAN WR G3 20K miles
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I have never heard of a ***8220;DEF / MPG***8221; error to give a DTC code.
 

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Hi all again, some follow up.
Used BimmerLink app after reading some of the recommendations from others in terms of how complete the code library is.
When I initially connected there were all sorts of codes in the memory for all sorts of things. After going through them there was nothing obvious. I cleared them and figured new ones would be of the greatest interest.
I've driven around 50 miles since the clear and the only particularly relevant motor based code is a 26CF00

26CF000 - fuel pre-supply pressure control, pre-supply pressure too low/positive control deviation. I'm not seeing anything on the RCM error returned by ODBWhiz.

The symptoms I have are low MPG and excessive use of DEF. I avoided the dealer when they said it was cost $160 to read a code and $460 to replace a wheel bearing. I did the wheel bearing (cost $100 all in and about an hour of time), but I'm beginning to think I may be more dependent on a diagnostic from them than I want.

Any suggestions on the code? Seems unrelated to the DEF/MPG issue. It also feel that the DEF/MPG issue is not dropping a code...or I've not driven far enough.

any final thoughts before I grab my ankles at the dealer?
Hmm... You're getting a code that directly implies that the DDE believes the fuel pre-supply system is NOT providing enough pressure, where POSITIVE deviation of the control loop has been exceeded, where this pre-supply fuel system directly feeds fuel to the high pressure fuel system, which feeds fuel directly to the injectors, which are used to put fuel into the engine's cylinders; however, you somehow illogically believe the DDE exceeding its ability to supply INCREASED QUANTITY OF FUEL to compensate for the supposedly low fuel pressure from the pre-supply system, to be unrelated to your engine stumbling under hard throttle & excessive FUEL consumption, where DEF usage is directly proportional to fuel consumption...

I would agree that you should pay the money for a proper diagnosis from the dealership... My speculative guess, based on the very limited info provided, considering that you report that your fuel mileage is reduced & DEF usage is high, is that the pre-supply pressure sensor is faulty, where the DDE falsely believes pre-supply pressure to be low... This guess is as good as how much it cost you in time to diagnose & relay info though... On an E70 35d, pre-supply pressure should be around 3900mBar at idle, not sure if it's the same for your vehicle.

I would also guess that some of the recurring codes that you hinted at seeing, but deemed irrelevant & thus didn't post, are actually relevant...
 

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Discussion Starter #19
Updates despite the time lapse

Hi all,
wanted to say thanks again for the help in determining the problems with the 328d.

Here's an update and an answer to some questions. The issue has not been fixed but I have new avenues to examine.

First off, the DEF usage. I've got to confirm it with a refill but it appears to be a sensor in the passive tank stating empty when it was full. I don't know the DEF tanks cumulative capacity but the issue would have prevented the passive from refilling the active due to sensor saying tank was empty. I was quoted a smidge under $1600 to replace the tank along with the sensor. Having dealt with the DEF fluid before I took a gamble and asked them to rinse out with hot water. Sensor is back to working and I suspect my DEF usage will be back to normal. To be confirmed.

Next, the low mpg. I'm around 35-38 on highway runs when I used to struggle to go below 45mpg. Mechanic changed the fuel filter and said it was both dirty and had tiny metal particles in it. He said there was a recall on the high pressure fuel pumps for failures like this and to take it to a dealer. It made some sense - fuel rail not getting enough pressure and because of the design, it could lead to lower pressure in the injector such that at high load it misfires. Oddly, there are no codes other than the low fuel pressure I'd mentioned earlier in the thread.
I've done a quick search and only found fuel pump recalls on gasoline engines. Can anyone confirm the same on diesel fuel pumps?
Has anyone here had this issue? If so, what was the action?

thanks and nice to be back.
 

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Tiny metal particles in the fuel filter sounds bad to me. I know of no recalls on diesel high pressure fuel pumps, but do know of people having HPFP failures with tiny metal particles due to someone having tried to run the engine with a tank full of gasoline, resulting in destruction of the HPFP. Maybe not your issue here, but I don't like the sounds of this.
 
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