Designation and processor
A service-manual chapter on engine electrical systems describes Motronic M4.1 alongside M1.5. It does not establish the processor type for a particular M4.1 board; the 8051 identification remains unverified here.
Identification and scope
Record the Bosch and vehicle-manufacturer ECU part numbers, engine code, market, year, hardware and software identity. Identify the processor from the specific unit before relying on its architecture. No pinout, interchangeability or programming procedure is established by a family designation alone.