Hi @v-jefferni ,
sorry for my late reply and thank you very much for your help!
Just wanna explain may full problem:
1. My datasource is a CSV file with ANSI encoding. Here I have some Records like this:

So there are some Special characters from SAP datasource, original Record should be: "########Spedition Mickeleit Gm45329"
2. Reading with Power Query looks like this:

There are now special characters inside...
3. Now I'm trying to integrate my Records to Datavers via Dataflow, but get the following error message:
Reason: Bad Request, Header x-ms-client-request-id 2f2bec2d-955b-42c6-869c-e6da423d4b0b, Error code: 0x80040278, Message: Invalid character in field 'crefb_customer': '', hexadecimal value 0x01, is an invalid character."
So how to replace this record when I can't see the characters in Power Query?
BR,
Sven