# F11 2011 AHM Trailer Module Coding



## nickbg (Nov 17, 2016)

Hi,


One of the faults I am getting is CF2501 status trailer, 0x2E4) receiver EGS, transmitter AHM.

I am not aware that the car has ever had a towbar fitted, but i can't be certain. Do you have any experience of disabling AHM ? and what is involved. It would appear that EGS is expecting a response from it and its not happening.....

Cheers
Nick


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## agent_orange (Apr 21, 2019)

Bumping this 4 year old thread because I have the exact same fault on an F25.
Although in this case unlike the OP I know what the cause is, having removed a Westfalia tow module and wiring from this car.

From a bit of reading, it looks like AHM needs to be removed from the VO using E-Sys?
How much work and module flashing is involved in that?
Hopefully not much considering that installing the AHM module took no flashing or coding at all, was plug and play.

I do have E-Sys 3.27 and full PSdZ data but have only used it for FDL coding so far.
Have the "Upgrading ECU***8217;s on BMW F11 520d" ECU flashing guide but haven't taken the plunge yet.

Any guidance would be much appreciated.


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## jjan (Oct 21, 2015)

No need to program. Remove 235 or 3AC from VO and code al the modules. You don’t know witch modules have been coded in the past so to be sure code them all. 

It’s an easy job. 

There are guides you can use to add a VO. It works the same, just remove a VO instead of adding one. 

Psdzdata lite is enough 


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## jjan (Oct 21, 2015)

If there are no 235 or 3AC in the VO, don’t change anything to the VO, just Code the car to default, maybe someone did fdl coding after Ahk was installed 


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## agent_orange (Apr 21, 2019)

Thanks jjan.

There was no 235 or 3AC in the VO.
This car did not come from factory with a tow coupling or wiring, but had an aftermarket Westfalia one fitted about 2 years ago which I removed recently.
I have coded all modules anyway, but it only succeeded in removing all of my FDL coding changes, which I knew it would.
I'm 99% sure that nobody other than me has done FDL coding on this car.

The CF2501 persistent error on the EGS module about the AHM is still there.
Any ideas on what to try next?


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## jjan (Oct 21, 2015)

Sorry, no other ideas. If the fault doesn’t give any problems, just let it stay there. 


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## BimmerSLO (Nov 19, 2017)

Hi guys!!
I have a question regarding same error code.

Although,

I have installed Westfalia retrofit tow bar with dedicated electronic for F15 X5. Manual says no coding is required. I have connected two positive wires with breakers, 3 negatives, CAN high, CAN Low, contact plus 12v, and stop lamp... All by the book from westfalia manuals.

All works fine, lamps work nicely, even tow bar is shown on PDC when connected.

But....
I do get


CF2501No message (status, trailer, 0x2E4), receiver EGS, transmitter AHM

error code. 

I assume that car knows from can that tow bar electronics is connected, but EGS does not get any info from AHM. AHM module is Westfalia, not OEM. Should I code tow bar in?? Should I just leave it alone? Fault code is permanent and does not go away by clearing codes in ISTA.


Thanx!

BimmerSLO


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## BimmerSLO (Nov 19, 2017)

So... as I did some more research on this issue, I found on German edition of motor-talk forum that it is a known issue on some (15 vehicles) where Westfalia does not communicate properly and it is sugested that OEM module and wiring is installed....

I found out that coasting on ECO PRO is disabled as well even when no towing is attached.


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## BimmerSLO (Nov 19, 2017)

So for now, Westfalia responded that their module does not communicate with car and they can not do anything with an issue…


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## agent_orange (Apr 21, 2019)

Thanks for the info and update, even if it isn't good news.
The other option like you say is to use the BMW module and wiring kit instead of the Westfalia, but that has other disadvantages apparently, including incompatibility with LED trailer lights.
And the CF2501 error remains even after removing the Westfalia module and VO-coding EGS.


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## MaWe (Oct 29, 2021)

BimmerSLO said:


> Hi guys!!
> I have a question regarding same error code.
> 
> Although,
> ...




Hello,


I have the same problem on F31 from 2013.

I installed the tow bar from westfalia.

Since the installation this tow bar I have problem with my automatic transmision.

When I stop on, after about 15 secondsI I feel a tug. When I disconnect the westfalia module everything is ok.


I'll try to code FA 3AC - nothing has changed, additionally I have on dash error of elektric trailer wiring
I'll try to code K235 - nothing has changed, additionally I have on dash error of elektric trailer wiring

Can anybody help ?


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## 1aBimmer (Sep 26, 2014)

Hi Guys..
Same problem here.. I did a succesfully (genuie) tow hitch retrofit on my F10 but short after I decided to remove it by reversing all VO coding
but then i got..
CF2501 - No message (status, trailer, 0x2E4), receiver EGS, transmitter AHM

after digging a little bit I found that a Tool32 job (CAN learning reset) could soleve the problem..

*Tool32*, Job: *GSB231*, *steuern*, Select arg: *CAN_LERNFUKTION_RUECKSETZEN* and here I have to put a value on the red field which I dont know what?

And since tool32 is such a powerful tool then Im not realy comfedent to run the job without knowing for sure which value shloud I put?!

Any advise?

Regards


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## sondreef (6 mo ago)

I have the same problem with my E61 after removing the westfalia module. Did you find any solutions to this problem?


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## 1aBimmer (Sep 26, 2014)

sondreef said:


> I have the same problem with my E61 after removing the westfalia module. Did you find any solutions to this problem?


Unfortunately not yet!


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## 1aBimmer (Sep 26, 2014)

1aBimmer said:


> Hi Guys..
> Same problem here.. I did a succesfully (genuie) tow hitch retrofit on my F10 but short after I decided to remove it by reversing all VO coding
> but then i got..
> CF2501 - No message (status, trailer, 0x2E4), receiver EGS, transmitter AHM
> ...


Hi guys..

I just solve it by putting “ja” in the red field and ran the job and it instantly reset CAN learning.. then cleared the error by ISTA.

Cheers


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