What computer needs replaced. The Engine computer or trans computer there are a few. if you could go into more detail it would help more. but if its the dme (digital motor electronics module) you cannot do it yourself. nor can you do the trans module yourself. becasue both of them have to be coded to the car that way it know which engine and what type of options your vehicle has. then it has to be aligned with the electronic driveaway protection moduel (EWS). I'm not for sure on this but i think the only machine that can do this is the gt1 or the DIS diagnosis machines. (zibby knows everything about every bmw so pm him and ask him)it the part that is actually most of the expence.