Its located in the trunk. If you open the boot and look on the RHS (assuming RHD vehicle) then there is a panel that you can clip off. Once removed you will see a black unit around 10cm x 10cm with 3 connectors going to it. One connector is for the front sensors, one for the rear and the third for power/comms to the rest of the vehicle. I had an issue on my system which was pinpointed down to a break in the wiring to one of the rear sensors - it took the dealer weeks to find it though. I got a friend to check the fault codes which pinpointed it down to the sensors but the dealership went full circle, i.e. replace the module, update the software, etc and only really took my advice into account when I started getting firm with them - wasted a lot of unnecessary time, money and effort. Goodluck !