# DDE not recognizing MAF



## Bearded335d (Feb 21, 2017)

I've only owned my 2011 335d for 6 months. It started throwing cut engine power(limp mode) on dash. I brought it to a recommended BMW mechanic. They had it for 4 days trying to diagnose the problem. Today they said the mass airflow was sending signal to DDE, but DDE was not reading mass air flow(MAF). Not confident but he recomends replacing DDE($2300). I've read allot on conflicting info. Anyone have any light on the issue???


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## Doug Huffman (Apr 25, 2015)

.


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## Hoooper (Jun 17, 2013)

Bearded335d said:


> I've only owned my 2011 335d for 6 months. It started throwing cut engine power(limp mode) on dash. I brought it to a recommended BMW mechanic. They had it for 4 days trying to diagnose the problem. Today they said the mass airflow was sending signal to DDE, but DDE was not reading mass air flow(MAF). Not confident but he recomends replacing DDE($2300). I've read allot on conflicting info. Anyone have any light on the issue???


If you NEED to replace the DDE you can do it for a lot cheaper than $2300. A used DDE is perfectly fine and those are going for around like $300 on car-part.com, I dont think it takes $2000 to program it to your car.


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## Frediesel (Apr 28, 2012)

Do you know what codes it was throwing? Do they know for sure that it's not the MAF sensor?


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## Bearded335d (Feb 21, 2017)

Hoooper said:


> If you NEED to replace the DDE you can do it for a lot cheaper than $2300. A used DDE is perfectly fine and those are going for around like $300 on car-part.com, I dont think it takes $2000 to program it to your car.


He said $1700 for a new dde. And $600 in labor. This is all on top of the new battery, oil change, and diagnostic so far. Thanks for the link. I was curious about gambling with a used.

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## Bearded335d (Feb 21, 2017)

Frediesel said:


> Do you know what codes it was throwing? Do they know for sure that it's not the MAF sensor?


I'm not sure exactly what codes yet until he gives me a walk through. Said MAF is sending a clear signal to dde.

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## ingenieur (Dec 26, 2006)

DDE's are rarely the cause of a power reduction - get the codes and post them.

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## Nadir Point (Dec 6, 2013)

Why not start by just re-flashing it?


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## Bearded335d (Feb 21, 2017)

Codes Thrown:

-AOCI (all letters)
-9CD5
-4DC2
-4BC6
-931D
-A559
-4831

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## robnitro (Aug 3, 2016)

What the dealers charge is virtually a crime.


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## Doug Huffman (Apr 25, 2015)

Bearded335d said:


> Codes Thrown:-AOCI (all letters)


DTC are written in hexadecimal = 0123456789ABCDEF. A0C1


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## ard (Jul 1, 2009)

Wait.

So this 'recommended BMW mechanic' cleared the codes, drove it, and ALL of them came back?

Did he run any BMW test plans? Or does he only have a code reader?

You say the battery was replaced...when? Why?

I would bet a large amount of money the DDE isn't the issue.

Button it up, clear the codes and see which return. (A failing battery and/or alternator can throw odd error codes. If you just replaced the battery, see how it goes)

I am suspicious about this mechanic- seeing a signal at the MAF, and when the DDE doesn't response then assuming the DDE is bad seems pretty sketchy.

Maybe a dealership visit would be worthwhile

I'll look at the codes tomorrow


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## Bearded335d (Feb 21, 2017)

ard said:


> Wait.
> 
> So this 'recommended BMW mechanic' cleared the codes, drove it, and ALL of them came back?
> 
> ...


Thanks! I'm meeting with him tomorrow for a run through. I'm not sure he did clear the codes. I'll have him reset it tomorrow. I was also going to ask to see if he could scope the intake and MAF to check build up. All advice is appreciated. They have had the car a week now :/

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## CVX.mne (Feb 19, 2017)

Believe it or not. Bad quality battery can cause all sorts of strange problems on Bmw.

Replacement old battery (which by the way, worked just fine. Car was starting perfectly) 
with good one - solved the problem in my case.


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## CVX.mne (Feb 19, 2017)

Believe it or not. Bad quality battery can cause all sorts of strange problems on Bmw.

Replacement old battery (which by the way, worked just fine. Car was starting perfectly) 
with good one - solved the problem in my case.


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## Nadir Point (Dec 6, 2013)

cvx.mne said:


> believe it or not. Bad quality battery can cause all sorts of strange problems on bmw.


+1


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## ard (Jul 1, 2009)

OP could get royally screwed here- just due to a 'recommended' mechanic not being very good.


(OP, there is a SPECIFIC REASON that I ask certain questions. If you answer these questions carefully, it may result in a diagnosis moving forward. I asked about the battery.....)

I agree with others that battery/charge/charging issues can cause very odd errors.

So with that silly list of errors, there is one scenario:

Battery is failing
BMW system tries to manage charge, but some modules don't get adequate power and throw errors.
Shop gets car, sees the battery is low.
Shop pulls codes
Shop fails to reset codes, drive the car and see what happens
Shop is now looking at codes that MIGHT have been caused by voltage issues
Shop not having BMW software- rather shop has code reader and "scope'...shop TRIES to diagnose using their old methods of looking at signals, but doesn't really understand how this modern diesel DDE works- they GUESS it must be the DDE.

So, when was the battery replaced? Why? Correct battery?

If you just want to let them yak at you, and you are going to try and make sense of this decision based on what you will have on hand during this 'walk through', good luck



IMO you need to:

1. have him tell youi what each code is- this is a DIESEL, with a BMW DDE. You cannot use a generic OBD. You need BMW specific code definitions

2. Confirm that he cleared all codes and the above codes ALL came back

3. If the list above is not 'fresh', when did they occur? (Usually listed by 'engine operating hours')

4. Have they run any BMW testplans to assist? Why not? Do they not have access to BMW diagnostic software?

If you are paying $40 an hour, then that's fine. But if this is retail automotive, you need a shop that is outfitted for modern BMW diesel systems. Not 'scoping' signals. (Based on the price of the DDE and the labor, you are paying super retail. Just go to a dealership)

Another thought- the MAF in the diesel isn't used the way it is in a gasser...in a gas it helps set the AFR, and is central to the engine performance. In a diesel, it is used for the EGR system...


Finally, you may feel 'trapped': you've taken it to this shop, this BMW diesel may be over their heads- a dealership might be the better choice- BUT you will have wasted $$$ to get the car back now. The old 'good money after bad' thing....


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## Bearded335d (Feb 21, 2017)

ard said:


> OP could get royally screwed here- just due to a 'recommended' mechanic not being very good.
> 
> (OP, there is a SPECIFIC REASON that I ask certain questions. If you answer these questions carefully, it may result in a diagnosis moving forward. I asked about the battery.....)
> 
> ...


I took your advice. They cleared all codes and started from square one again. They said they did use bmw diagnostic software "can't remember the name". They called two business days later and said its ready... Apparently it was the MAF sensor all along. So with new battery"replaced because it was not taking a full charge", oil change, and replaced MAF was $1100

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## Doug Huffman (Apr 25, 2015)

Bearded335d said:


> I took your advice. They cleared all codes and started from square one again. They said they did use bmw diagnostic software "can't remember the name". They called two business days later and said its ready... Apparently it was the MAF sensor all along. So with new battery"replaced because it was not taking a full charge", oil change, and replaced MAF was $1100


A late model BMW will never fully charge its battery. It is designed that way to prevent damaging the battery.

A BMW shop that doesn't remember the name of the software is alarming. But they got their money and probably didn't even use any lubricant, certainly that they charged you for. Did they even kiss you?


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## ard (Jul 1, 2009)

Bearded335d said:


> I took your advice. They cleared all codes and started from square one again. They said they did use bmw diagnostic software "can't remember the name". They called two business days later and said its ready... Apparently it was the MAF sensor all along. So with new battery"replaced because it was not taking a full charge", oil change, and replaced MAF was $1100
> 
> Sent from my iPhone using Bimmerfest mobile app


Shockingly incompetent....

They'd have taken your money and much more. Battery, oil change and MAF for 1100? Hmm.


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## Flipxcru (Oct 17, 2016)

Doug Huffman said:


> A late model BMW will never fully charge its battery. It is designed that way to prevent damaging the battery.
> 
> A BMW shop that doesn't remember the name of the software is alarming. But they got their money and probably didn't even use any lubricant, certainly that they charged you for. Did they even kiss you?


Lol! In all seriousness, no need for this kind of sarcasm, sir!

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2015 VW Passat TDI
2011 BMW 335D


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## ard (Jul 1, 2009)

Flipxcru said:


> Lol! In all seriousness, no need for this kind of sarcasm, sir!


Sarcasm??

He was serious.

:angel:


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