Can anyone advise where I should start looking to solve this? I was told it was one bumper sensor and replaced it to no avail (maybe a fault cleardown is needed?). There is a main control unit for the sensors somewhere. I get this fault immediately after I select reverse gear.

  • Welcome to Motor Vehicle Maintenance & Repair! Do you have the exact fault code which popped? Commented Jan 11, 2018 at 9:06
  • no, it just says "reversing system fault detected" Commented Jan 11, 2018 at 11:37
  • Curious how you knew the specific sensor was bad. Did fault codes get reset after it was replaced? I would start with that. If it faults again, then begin looking deeper.
    – CharlieRB
    Commented Jan 11, 2018 at 20:56
  • the peugeot tech told me which one. I was told "just replace it" but I do wonder if it needs cleaning out somehow. That was what was needed on my TPMS sensors Commented Jan 12, 2018 at 10:45

2 Answers 2


You say "one bumper sensor". I guess your car has multiple bumper sensors. There is a way of checking them one by one without any special tool. If in silent environment and with your ear close enough, you can hear a properly functioning ultrasound sensor making silent yet audible ticks.

See this video.

  • it has four embedded in the rear bumper. I was told the fault was with the inner left hand side sensor when viewed from the rear. They are wired rather than wireless, so I don't think they need to be coded. Commented Jan 11, 2018 at 11:39
  • What you mean by "coded"? Sure, they are wired. The procedure I wrote gives you a chance to test whether each of the sensors is basically dead. The control system is most probably able to recognize if one or more of the sensors are bad. So if that is the case, you can verify whether the cause of the reported error is (or possibly could be) any of the sensors being absolutely silent (no ticking), which would mean it does not transmit the ultrasound waves. For the sake of completeness, I'll add that the ticking is not the ultrasound itself (which is inaudible per se), it is just a by-product.
    – MaSlo
    Commented Jan 12, 2018 at 5:14
  • well, TMPS sensors have an id (yes, I know they are wireless) and it did occur to me that the control system might recognise an id in the (wired) reversing sensors and thus need coding in. I will however try what you suggest just in case the new part is dead, or another OE sensor has become faulty since Commented Jan 12, 2018 at 10:48

I could not hear anything, but thank you for the suggestion.

the answer is that they are simply wired and do not have an id. My solution was to buy a cheap laptop and Diagbox and solve it myself. If you run the trouble shooting it identifies which sensor is faulty although the translated french which indicates the positions is a little unclear and refers to left hand drive. I found that its easiest to rotate the sensor until the lugs disengage and then gently push it through from the outside as internal "grab space" is limited if you have big hands like me. I bought cheap lookalike sensors from ebay and they work perfectly well.

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