[jcordier]

I tried looking this code up and googling it but can't find a thing.

[Ibo24]

Is it a 330e or 335i Active Hybrid?

[jcordier]

Originally Posted by Ibo24

Is it a 330e or 335i Active Hybrid?

Just a 335i

[Ibo24]

Do you have any issues onboard?

Like any fault messages etc?

[jcordier]

Originally Posted by Ibo24

Do you have any issues onboard?

Like any fault messages etc?

I added a drop in filter from afe and replaced my oil cooler gasket and ofhg. Ever since I've gotten those codes. But they clear. The dc to dc doesn't want to clear though.

[atzebmw]

Originally Posted by jcordier

I tried looking this code up and googling it but can't find a thing.

Here the fault description from ISTA:

Fault description
Diagnosis monitors the DC/DC converter (support for voltage supply of head unit during engine start for vehicles with automatic Start-Stop function) and the signal line between the front electronics module (FEM) and DC/DC converter.

The fault is identified when there is an open circuit, short to B+ or B- on the signal line or when the DC/DC converter signals a fault.

Condition for fault identification
Supply voltage greater than 8.5 V

Terminal 30B on


Condition for fault memory entry
The fault code is entered whenever it exists for 100 ms.

Action in service
Check line and plug connections between FEM and DC/DC converter for short-circuit and open circuit.

If the wiring and the plug connections are OK, replace the DC/DC converter.

Fault effect and breakdown warning
Possible malfunction of head unit (audio, video, navigation) while starting engine (MSA).


Driver information ------------
Service instruction -------------


If there are no problems, i would not take the error seriously or read the error memory with another program.

[jcordier]

Thank you for the detailed description. Under the action in service. Do you know anything about where those parts are. I haven't ever heard of the FEM or a dc/dc converter before.

[atzebmw]

Originally Posted by jcordier

Thank you for the detailed description. Under the action in service. Do you know anything about where those parts are. I haven't ever heard of the FEM or a dc/dc converter before.

Here the description of the DC/DC Converter and the location.

https://www.newtis.info/tisv2/a/en/f...erter/GGlzwmNo

Here the wiring diagram (A173=FEM, N5=DC/DC converter).

https://www.newtis.info/tisv2/a/en/f...erter/GRyPpin9

Here an instruction how to get to the FEM.

https://www.newtis.info/tisv2/a/en/f...les/1VnYgUVO8c

[jcordier]

Originally Posted by atzebmw

Here the description of the DC/DC Converter and the location.

https://www.newtis.info/tisv2/a/en/f...erter/GGlzwmNo

Here the wiring diagram (A173=FEM, N5=DC/DC converter).

https://www.newtis.info/tisv2/a/en/f...erter/GRyPpin9

Here an instruction how to get to the FEM.

https://www.newtis.info/tisv2/a/en/f...les/1VnYgUVO8c

Thank you!

[jcordier]

That other code went away, but I just used bimmer code and now there's new code that won't go away. Any help is appreciated.

[jcordier]

Originally Posted by jcordier

That other code went away, but I just used bimmer code and now there's new code that won't go away. Any help is appreciated.

Nvm. I got it to delete the code once I turned my ac off and turned the engine off. Once I started it back up. It magically disappeared.

[ready750]

Originally Posted by atzebmw

Here the fault description from ISTA:

Fault description
Diagnosis monitors the DC/DC converter (support for voltage supply of head unit during engine start for vehicles with automatic Start-Stop function) and the signal line between the front electronics module (FEM) and DC/DC converter.

The fault is identified when there is an open circuit, short to B+ or B- on the signal line or when the DC/DC converter signals a fault.

Condition for fault identification
Supply voltage greater than 8.5 V

Terminal 30B on


Condition for fault memory entry
The fault code is entered whenever it exists for 100 ms.

Action in service
Check line and plug connections between FEM and DC/DC converter for short-circuit and open circuit.

If the wiring and the plug connections are OK, replace the DC/DC converter.

Fault effect and breakdown warning
Possible malfunction of head unit (audio, video, navigation) while starting engine (MSA).


Driver information ------------
Service instruction -------------


If there are no problems, i would not take the error seriously or read the error memory with another program.

Hi,
I have same problem after flashing all ecu except headunit, you say error is gone how did you resolve it?, is it by changing dc/dc converter ?
Thank you

[ready750]

Originally Posted by ready750

Hi,
I have same problem after flashing all ecu except headunit, you say error is gone how did you resolve it?, is it by changing dc/dc converter ?
Thank you

Hi,

Finally I boat a new dc conveter, a surprise when I want change it, my car doesn’t have dc converter, I don’t understand why ista show this error, is it possible that problem is in battery which is never change it (my car production is 11/11)

[ready750]

Originally Posted by ready750

Hi,

Finally I boat a new dc conveter, a surprise when I want change it, my doesn’t have dc converter, it’s included in fem, I don’t understand why ista show this error, is it possible that problem is in battery which is never change it (my car production is 11/11)

Update: 15/12/2020

Finally problem resolved by doing some FDL into dme ecu and fem ecu
Now into ista all is green