I'm not sure why, but this just started today, I turned on my Nav as usual and the message appeared "Check park assist". I put the car in reverse and went behind to try and hear the sensors, and neither made a clicking noise like I've been told they should. Also, in the car there isn't the normal beeping sound when I backup. Would the problem be the sensors or wiring?

Cars & Trucks - Lincoln - Navigator - 2005 Lincoln Navigator