At times when driving my 2018 Nissan Altima, a safety warning comes on that indicates the front radar is unavailable due to an obstruction when there is clearly no obstruction. A warning light stays on and then, once the car is turned off, it resets. I'm planning to take car in to dealer for regular oil change and then ask about this issue from Nissan perspective. At this point, there have been no safety issues, except one can get startled when this warning goes off. I'm getting used to it now that it has happen a dozen or more times.