With all four back up rear bumper sensors completely clear of any visible external ice or moisture, whenever it gets below 20 degrees F, sonar sensor goes into constant alarm on my 2015 Frontier SV CC when it's in reverse. It can be silenced by pressing the defeat switch on the panel, until I stop and start the truck again. I was able to identify which sensor was causing the problem with a hair dryer. Just sequentially warmed each one up for a minute or so while in reverse (brake on, wheels blocked!) and alarm screaming, and wait for the alarm to stop. In my case it was the 2nd sonar sensor unit in from the left side.
If your truck is still under warranty, be warned that your dealer will likely resist any suggestion the part should be replaced under warranty, with statements like "they need to diagnose the problem" (in their warm shop where problem will never occur), or "there must have been ice on the sensor" after you tell them there was no ice, or "there must have been some moisture in the sensor" as if these sensors should not be water-proof, or "it might be a bad connection or maybe the control unit," all ending with a report they could not duplicate the problem.
The replacement sensor part is outrageously expensive (listed on Nissan parts for $276.10 each), and so far I have not found a location diagram or other description that says exactly which of the listed alternative Nissan parts goes where (259949BF1A, or -B, -C, -D also listed respectively as part numbers 25505P, or -PA, -PB, -PC), which makes it difficult to justify purchasing a replacement part to see if that fixes the problem. Anyone know which part numbers go where?
It is possible that there was condensation moisture inside the sensor that was driven off by heating with the hair dryer, but the problem keeps occurring when the temp goes below 20 degrees F, so obviously, it that's true, the sensor is not properly sealed. Next time I will make a recording of the alarm and how the alarm stops when a particular sensor is warmed up, and present that to my dealer before the warranty ends. It will be interesting to see what excuses they come up with and whether they actually fix the problem or try to just waste my time with an series of burdensome appointments to see if I go away or the warranty times out. It is amazing to me that a company would risk their next sale to me and others that read columns like this to save a few paltry bucks.
If your truck is still under warranty, be warned that your dealer will likely resist any suggestion the part should be replaced under warranty, with statements like "they need to diagnose the problem" (in their warm shop where problem will never occur), or "there must have been ice on the sensor" after you tell them there was no ice, or "there must have been some moisture in the sensor" as if these sensors should not be water-proof, or "it might be a bad connection or maybe the control unit," all ending with a report they could not duplicate the problem.
The replacement sensor part is outrageously expensive (listed on Nissan parts for $276.10 each), and so far I have not found a location diagram or other description that says exactly which of the listed alternative Nissan parts goes where (259949BF1A, or -B, -C, -D also listed respectively as part numbers 25505P, or -PA, -PB, -PC), which makes it difficult to justify purchasing a replacement part to see if that fixes the problem. Anyone know which part numbers go where?
It is possible that there was condensation moisture inside the sensor that was driven off by heating with the hair dryer, but the problem keeps occurring when the temp goes below 20 degrees F, so obviously, it that's true, the sensor is not properly sealed. Next time I will make a recording of the alarm and how the alarm stops when a particular sensor is warmed up, and present that to my dealer before the warranty ends. It will be interesting to see what excuses they come up with and whether they actually fix the problem or try to just waste my time with an series of burdensome appointments to see if I go away or the warranty times out. It is amazing to me that a company would risk their next sale to me and others that read columns like this to save a few paltry bucks.