P126F29 - THE SIGNAL 'HOT START' FROM THE AUTOMATIC ENGINE START/STOP SYSTEM HAS A MALFUNCTION. THE SIGNAL IS INVALID.

[Dima]

Hi,
I have a Mercedes e350 CDI, W212, 3.0, 2012 - since I bought it the start/stop system has never worked.
Onboard cars, I show the ECO symbol but it is yellow-hearted. I did a test with the tester and I showed this error code: P126F29 - THE SIGNAL 'HOT START' FROM THE AUTOMATIC ENGINE START/STOP SYSTEM HAS A MALFUNCTION. THE SIGNAL IS INVALID.
Can this problem be related to the two batteries (the main battery and the auxiliary battery), or to another electrical part of the car? how can I solve this problem?
Thanks.

 

[Larkone]

Batteries are the first to check, then onto STAR for proper diagnostics

 

[AndrewOl]

Hi, if it has never worked and you didn’t have from new a previous owner may have disabled the system to avoid having to switch it off each time the car is started. If the batteries check out ok this may be your issue.

 

[Dima]

I went to the service and they changed my battery, and everything works perfectly. Thanks to everyone for the advice