2006 B class Parking Sensors

[BClass2006]

Hi All, i have a 2006 B Class, the parking sensors have gone nuts in the last few days, they show orange lights and then within about 5 seconds they go to 2 red lights front and back (with no beep), all the sensors make the ticking noise so all seem to work, in the split second the system works all the sensors register so they are working. Any ideas what may be causing this? I have cleaned all the sensors, also where is the parktronic module located?

thanks