Think there is a thread or two somewhere on this issue. Had same issue with my 2015 RAM 1500 Laramie about four months ago.
Checked all connections - unplug, blow out with air to ideally ensure they were dry. Reconnect. No joy, same issue.
Ordered new sensors via Amazon. There were a few choices back then. Although not available, today, here is what I ordered.
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https://www.amazon.com/gp/product/B01HO64F1C/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
A couple things to note.
1. These sensors are black, not the silver on my Laramie.
2. Part number did not exactly match my OEM. One digit off or something. Q&A area said they'd work on my truck. So, I ordered them. Perfect fit in sensor holder. Electrical connector quick disconnect slightly different -
physically fit on tightly, but would not "click" securely. Two of six "clicked". Hmmmm. So I applied electrical tape hoping it would keep connectors from vibrating loose.
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30 seconds after starting the truck, "Service Front Park Sense" went away. Tested each sensor at varying distance. ALL work fine. Four months later, Northern NV winter has ended and NO ISSUES with sensors. Work just fine.
Packages I ordered have four sensors. My truck has six. As I did not want to Easter egg search which sensor was bad, I replaced all six. Ordered two packages of four. $62.10. Arrived with a few days.
As I understand it, OEM sensors are ~$250 or more. So I opted for trying $62 solution. Time wise about 30 minutes disconnecting sensors and blowing them out with air. Actual replace sensors less than 60 minutes. Easy peasy.
Good luck with whatever solution you pursue.
