When you switch a ECU in a focus, obviously you have to have the new ECU re-keyed to work with your current keys/ignition. My question is, if you replace it with a junkyard ECU, do you have to reprogram it to match your cars VIN number(changing parameters back to your OEM specs) or can you keep the pulled ECU s VIN and parameters and just re-key? Assuming you grab a ECU from a focus with the same engine.
Read more: Switching a ECU in a 05 Ford Focus?
