Get a diagnosis done on Peugeot Planet or Diagbox and it will tell you which sensor is faulty. If one is faulty then none will work. Also visually check that one of the sensors hasn't been pushed in or is damaged.
No problem. I had exactly the same fault on mine so I speak from experience! It was diagnosed on a friend's laptop who had Diagbox and it came up as "front right outer sensor short circuit to positive". Bought a sensor on eBay and changed it (after a bit of a struggle), problem solved! Good luck with yours.
Search on the forum for Peugeot Planet Map to find a member near you with diagnostic software, they will help you.