How to replace BMW E series DME/DDE

BMW ISN Reading and ISN writing
BMW ISN Reading and ISN writing

ECU which controls the optimal performance for engines in BMW Engines is called DME (Digital motor electronics) in gasoline engines and DDE (Digital diesel electronics) in diesel models. All these control modules come with a specific internal security number (ISN) for handling unauthorized operations. Each specific car in BMW has a unique security number inside ECU for mishandling.

Replacing these controls before developing auto diagnosis tools like AUTOHEX was a very much time-consuming and pricy procedure. Autohex allows users to break down these securities for ECU and match ECU in a safe and simple method by the functions that allow reading ISN and writing ISN.

Autohex allows users to read ISN (security number) stored in one ECU and either edit (read/write ISN) or match with other controls (read ISN from original, write ISN to donor) within the car. By this, you will be able to match most of the DME/DDE in both BMW and MINI with new or used secondhand one from one model to another.

For replacing Engine control module with a brand-new unit connect the new one and do flashing the ECU from Indiv programming a function within Autohex. For procedures for replacing used units just follow as mentioned below.

How to replace E series DME/DDE

AutoHex is the best ISN reader Software in the market. Almost all DME/DDEs in E series can be replaced with a secondhand just by reading ISN (Internal security number) from the Donor and writing it to ISN for CAS. Only in some E series models (X5, X6, and later models of E84) with 8HP transmission, you can’t follow this procedure. In those cases, must try to write to DME/DDE from ISN manager or use ISN factory mode or onbench MSD8xx option on continental DME for changing donor control ISN with respect to the car.

Follow these steps for matching DME with the car

  1. Connect secondhand DME
  2. Go to ISN manager from Coding/programming
  3. Click on option 1 for reading DME SK
  4. Read and save SK to computer local disk
  5. Go to option 2 in ISN manger 
  6. Read CAS ISN
  7. Load the already saved DME SK 
  8. click on Start for write SK to CAS
  9. Do coding for DME.
ISN reading from CAS
ISN reading from CAS
ISN reading from DME or DDE
ISN reading from DME or DDE

Engine Synchronization

In the case of some old models DME will have only 4 digits as DME ISN, for these types users should manually swap the last 4 digits of CAS ISN with DME (no need to bother about CAS SK). Even after matching ISN with CAS these model cars will not start sometimes. In these cases, you should do DME CAS alignment from service functions.

DME short ISN
DME short ISN
DME CAS alignment in Autohex II
DME CAS alignment in Autohex II


Last Update: 6/5/2022
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