I thought that was normal. I've had my unit just a little over a year now and ever since I first installed the monitor (sensors were installed at the factory) I have had an issue with the monitor showing dash lines after a while as I'm driving down the road. At the next stop, when I start out again, I have pressure readings. Then several miles down the road, back to the 0.00 or -.-- . I just thought that was the way the system worked. At Goshen last year I got the antenna extension from you and installed it at the rear bumper, but it has not changed the issue of having no readings on the display after driving a while.