Relatively easy surgery. I think your ECU is located above your glove box. Easiest way to do this operation is to remove your glove box. There should be a vinyl cover above it. Remove this and your ECU should be right there. As a precaution, you could always disconnect your battery before you remove the ECU. As for myself, the ECU on my euro635 is in the same place. On my 750 it's in the engine compartment and I did not disconnect the battery when I removed my ECUs to chip it. where in the bentley book does it tell you how to remove a ecu. also is there a good chance of destroying the computer when you take it out. thanks