Identification and variants
MS4X describes C166-based MS41 hardware and a common 256 kB flashable version. Its hardware list is incomplete; verify the installed unit rather than assuming every MS41 is flashable. MS4X reference.
Choose MS41.0, MS41.1 or MS41.2 for the documented engine/emissions context.
Documented 256 kB layout
| Start | End inclusive | Region | Size |
|---|---|---|---|
| 0x00000 | 0x07FFF | Bootloader / UIF | 32 KiB |
| 0x08000 | 0x0FFFF | Undocumented | 32 KiB |
| 0x10000 | 0x15FFF | Calibration | 24 KiB |
| 0x16000 | 0x1FFFF | Undocumented | 40 KiB |
| 0x20000 | 0x3FFFF | Program | 128 KiB |
These are full-image offsets. MS4X reference.
For a raw calibration slice starting at 0x10000, a full-image address of 0x10020 would be offset 0x20 within that slice. This is address arithmetic, not an instruction to change the definition’s configured offset. Check the actual file format and XDF address basis first.
Calibration route
Use the MS41 map guide for fueling, ignition and idle entry points. Start with file identification and injector-data checks before modifying a working file.
Keep boot/identity information distinct from calibration work. Preserve undocumented regions in backups and comparisons; an undocumented label does not establish unused memory.
Sources and scope
Original reference notes by Tuning Wiki, informed by the linked MS4X Wiki pages. MS4X Wiki contributors and the authors credited by each linked project remain the source authors. Sources checked 10 November 2026. Suggested validation steps and worked arithmetic are editorial guidance; they are not a tested calibration or a claim of hardware verification.
- Siemens MS41 (revision 23746).
- Definition Files (revision 23632).