This is an advanced guide detailing a powerful method to flash modified firmware ("tuning files") and disable specific Diagnostic Trouble Codes (DTCs) on modern BMW DME/EDC ECUs using only E-Sys and a standard diagnostic interface. This technique bypasses the usual signature checks by temporarily using a special "patched" bootloader (BTLD) file.

The Principle: How It Works

Normally, E-Sys will reject any firmware (SWFL) that has been modified because the digital signature (checksum) will not match. This method works around that limitation in three stages:
1. Patched Bootloader Flash: First, you flash a patched bootloader. This special BTLD does not perform a signature check on the main software.
2. Modified Software Flash: With the patched bootloader active, you can now flash your modified main software (your "tuning file"). The ECU will accept it.
3. Restore Original Bootloader: Finally, you re-flash the original, official bootloader. The ECU is now back in a safe state, but the modified data from your tuning file remains active.

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CRITICAL WARNING: CHECKSUM (CHK) IS EVERYTHING!

The modified SWFL file ("tuning file") you create MUST have a correctly calculated checksum. For good CHK you can use WINOLS!!! 100% WORK !!!

IF YOUR SWFL CHECKSUM IS NOT CORRECT, THE DME WILL NOT BE CODABLE. After the flash, when you try to write the CAFD, you will get an error, and the process will fail.

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The Step-by-Step Workflow

Phase 1: Preparation

1. Open E-Sys and connect to the vehicle. Read the current software versions and identify your target DME's current BTLD and SWFL files from the SVT tree.
   
   
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3. Use a tool like our "PsdzData File Finder & Exporter" to easily extract the original SWFL file(s) you wish to modify.
4. Make a copy of this original SWFL and use your preferred editor (e.g., WinOLS) to make your modifications (e.g., DTC OFF, performance tuning).
5. Save the modified file with the checksums corrected. This is now your "Tuning SWFL".

Phase 2: The Flashing Process

1. Import the correct "Patched BTLD" from our library and your "Tuning SWFL" into your PSdZData folder. The target file structure within the SVT should look similar to this:
   
   
2. In E-Sys, calculate and execute a TAL to flash the DME with this combination.
3. IMPORTANT: During this first flash, E-Sys will likely show an error at the end of the BTLD flashing process. This is normal!
   
   
4. Do not panic. Simply restart the flash process in E-Sys again immediately. The second attempt will complete successfully, as shown in the log below.
   
   

Phase 3: Finalization & Restoration

1. After the patched flash is complete, you must restore the ECU to its original state for safety and future compatibility.
2. Replace the patched files in your PSdZData folder with the original BTLD and original SWFL files.
3. In E-Sys, execute one final flash with the original files.
4. After the final flash, perform default coding on the DME.

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The Comprehensive Patched BTLD Library

Below is the full library of patched bootloader files. Each file is provided with its size and a direct download link.


Future Development

Work is ongoing to add support for more ECUs, including M-series models. In the future, a software tool will be created to further simplify and automate this patch and dump process.

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System Requirements & Testing

• Operating System: This procedure uses standard BMW tools, which are tested and confirmed to be stable on Windows 10 LTSC 2019.
• Required Software: BMW E-Sys, a full PSdZData library, and a file editor like WinOLS.
• Required Hardware: An ENET Cable or ICOM interface.

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Disclaimer

This is one of the most advanced procedures that can be performed with E-Sys. It is for expert use only. An incorrect file, a bad checksum, or an interruption during flashing can permanently brick your DME. Always use a high-quality, stable power supply. Proceed at your own absolute risk.