The ecu is located in the rear of the engine bay on the drivers side (RHD models) you need to remove the top black cover, big phillips cross head screwsriver 4 screws. In here you will find the ECU, unbolt it and un plug it and on the top is written a number. the euc is usually the nearest to the windscreen in that boxOriginally Posted by gazz200581
Id have to question though the difference you would feel in a 520 and the state of the engine after 210,000 miles - depends on its maintenence history i guess