In a Renault Laguna 1.6 2003 , the ECU got damaged physically (the connector went off ) so i have to replace it with another one ( used ECU ) , I've read that I will need to disable the Immobilizer or decode the ECU ( or similar terms ) and the processes includes reading and altering the EEPROM or Flash Memory of the ECU.

Since I have the Old ECU would it be enough to just replace the old chips into the new ECU? Are there other things I should be considering during the replacement?

Inside the broken ECU :

enter image description here

  • More than likely, considering your car should be an OBDII car, there won't be any chips to replace. They are all hard wired in. I'm not sure about the immobilizer, but it sounds reasonable. I just don't have that much experience with Renault vehicles since I'm here in the States. Hopefully someone can give you some definitive advice on what you'll need to do. Commented Sep 25, 2015 at 14:53

1 Answer 1


I have replaced he old ECU ( SIRIUS 32N ) with another one ( SIRIUS 32 ) which is used before, the car has not started the first two tries but have started normally the third time, the immobilizer light have not been blinking which means there is no immobilizer problem and this means either the ECU is already decoded ( it is supposed to not be decoded according to the seller ) or the Immobilizer is a separate device that sends a confirmation to the ECU to start hence changing only the ECU won't create a problem.

the old ECU :

enter image description here

New ECU :

enter image description here

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