Category Archives: BMW

BMW E46 O2 Postcat Sensor Disable

Want to disable your post-cat O2 sensors?

Tested on: E46 with M52 engine and MS42 Siemens ECU!

  1. Download RomRaider from here; (alternative download link)
  2. Download Siemens Flash Tool from here;*
  3. Generate license for your copy of Siemens flash tool from here (free!) 
  4. Download ECU definitions .xml for your ECU (in our case – MS42) from here, free forum registration required (alt. link to the latest .xml)
  5. Siemens Checksum Corrector from here

* INTERFACE CABLE K+DCAN CAN USB OBD2 will be required. (search ebay about this);

  1. Connect interface cable to the OBD2 port in your car;
  2. Put the ignition key on position 2, do not start the engine
  3. Start Siemens Flash Tool (already installed & activated)
  4. Select “File -> Partial -> Read”

Now you have your .bin file. Now start RomRaider ECU Editor.

From menu ECU Definitions select “ECU Definition Manager”. Click Add and add your definition file

Now go in File menu, and “Open Image”, then select your .bin file (this one from Siemens Flash Tool)

Select “Configurations”, “Lambda feedback”, and choose option 1 /”Two precat lambda sensor or cat-preparation (SA199)”/

That is. Save this file with a new name. DO NOT overwrite your original file!

Run Checksum Corrector and load your new .bin file. You should see a message says “checksum was corrected”.

DO NOT MISS THIS POINT!!!! YOU MAY BRICK YOUR ECU IF FLASHING WITH A FILE WITHOUT CHECKSUM CORRECTED! (don’t ask how i know this….);

Ignition key to position 2, do not start the engine. Now run Siemens Flash tool, select “Partial -> Write”, and select your new .bin file. Wait a little till Flash Tool asks you to turn off the ignition key, and that’s all!!!

DO NOT INTERRUPT THE WRITE PROCESS BY ANY REASON!!! YOU WILL BRICK YOUR ECU IF YOU DO THIS AND YOUR CAR WILL NOT START!!!!!! I WILL BE NOT RESPONSIBLE IN ANY WAY FOR ANY KIND OF DAMAGES YOU MAY CAUSE USING THIS TUTORIAL! DO EVERYTHING AT YOUR OWN RISK! IT IS ALWAYS RECOMMENDED TO USE PROFESSIONAL SERVICES WHEN MESSING WITH YOUR CAR’S ECU!!!

NOTE: This may be NOT legal in your country! Please consult your local laws before do this. It is your responsibility!