My car developed a few electrical issues one of which is the immobiliser is not recognising the key. To drive the car I had to remove the immobiliser EEPROM (IC: L56R-93c56) on the ECU. The car drives fine but the engine management light is ON as well as there is a fault code P1607. Therefore I fitted a salvaged MICU and all the systems that did not work before work fine now apart from remote central locking (as immo EEPROM is missing) and green key flashing. I intended to solder back the original EEPROM however it got damaged either in storage or during unsoldering. Now my question is there a way to program immo EEPROM using code stored in keys? Or is there a “virgin” hex load that could be used to initialise syncing between ECU, immo and keys? Another worrying fact is that when I opened the old faulty MICU I noticed IC: IS93C46-3 1024-bit memory. I was under impression that in the 7th generation, Civic MICU is not serialised could anyone confirm? Additionally, I never paid attention to the fact that my old MICU R1 relay is missing. I believe it operates the magnetic clutch of the AC unit during the startup. Could anyone shine more light on its function? enter image description hereenter image description here

1 Answer 1


There is no virgin file for these floating around so you would have to buy a virgin ecu to copy it from. There is no point tho cause you'd still have to program it same as if using a used file.

Use this file on a new 93C56 eeprom for your ecu : https://autoelectronics101.com/tmp/civicl56ecudump.zip

After, you will need to use a diagnostic tool like Autel or dealers iHDS to run the "immobilizer/ecu/micu replacement" function. After that your ecu/micu/keys will all be synced and immo system will be back to normal with out the rom errors from ECU like your getting now with no eeprom installed.

The micu is part of the immobilizer chain so replacing it requires re-programming the immobilizer system same way I described above for the ECU. The relay missing in your micu is probably normal. They used the same pcb for different models. Your car probably just did not have what ever the function of what that relay controlled so it was not populated for boards with your part number. If your replacement has it then that means its not the correct part and may or may not have DTC's related to the added functions that are not present.

  • Thank you for your answer. I will try what you suggested while using Foxwell 2 inn 1 tool e.g. NT510 elite. Thank you for the file I will write the new EEPROM with it. Hopefully, it will go smoothly as soon as I make progress I will report the findings. Fortunately, the relay I mentioned was not present in the replacement MICU. So the new MICU fixed all the problems (apart from immo). One thing I have noticed is that the electric window on the driver's side remained powered on even without the key. I will assure the parasitic drainage to make sure that other systems are off.
    – Wintermute
    Commented Jan 11, 2023 at 23:59
  • Quick update. I fitted a new MICU. During installation, I noticed that MICU also has EEPROM (93c46) and ignored it for time being. With the new MICU fitted car drives fine apart from the engine management light being on and the immo key flashing as well as the remote central locking not working. I also tested EEPROM removed from ECU (93c56) with the new EEPROM reader and it turns out it is not damaged (initially I thought it was).
    – Wintermute
    Commented Feb 20, 2023 at 17:24
  • As soon as I fitted the original ECU EEPROM the car will not start (immo key flashing). This leads me to the suspicion that MICU is also serialised hence EEPROM on the MICU board (93c46). This could explain why with all original parts apart from MICU the car does not start. I intend to swap the MICU EEPROM from my old MICU to the new one. If for any reason it does not work can you provide me with a virgin hex file for MICU?
    – Wintermute
    Commented Feb 20, 2023 at 17:25
  • yes the micu is part of the immo chain. I do not have any virgin files for it sorry. Its pretty easy to just adapt it through obd2 tho.
    – narkeleptk
    Commented Feb 20, 2023 at 20:38

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