My meriva (B, 2011) has had a rear end shunt at some time, and had a replacement bumper,  car was specc'd to have the full front and rear park pilot,  it has the button on dash, but it's dead, 

the rear has a cheapo reversing sensor system installed, and i wanted to re-establish the factory park pilot system sometime.. i first thought the front bumpers been replaced too, and has no sensors in it... but no, the sensors are there and still wired up,  then i removed some trim panels in the boot,