I have a 2012 Expedition that has the 'check rear park aid' error come on the dash. I heard you can tell which sensors are bad by putting the car in R with the key on and the sensors should make a clicking sound. But I think that only applies to 2011 and older expeditions. My brother in laws expedition is the same year as mine and it works but doesnt make any clicking sounds. How else can I diagnose these little sensors. This happened after taking the car to the shop for some rear tailgate and bumper repairs and they were working when we took it in so I'm wondering if there is some sort of reset or something?

Thanks for lookin

 

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