I have a problem with my ECU not sending the signal most of the time to the fuel pump relay during cold weather below 42F and cold engine. Thus causing the car not starting. However, I have no problem in other conditions.

Do I need to reprogram and/or realign if I found an exact ECU?

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This post was auto-generated based upon a question asked on our tech article page here: Pelican Technical Article: BMW DME Motronic ECU Swap / Repair

Have you confirmed the fuel pump relay is the only component not being activated? The cold could be causing a DME or relay malfunction.

To answer your question, if you have an EWSII or later vehicle, yes the EWS will have to be aligned.

- Nick