My 2016 renegade is displaying service tire pressure system and shows the display with no pressures showing for all four wheels. I took it to the dealer today they tried to tell me I just needed to put air in the tires they said once they put air in that the pressures showed. They said that my problem was I wasn't driving the car to see the pressures come up that they always read blank unless you're driving. I argued with them that this was not the case and that the tire pressure system is showing this whether I'm driving or not and that if my tires are low it should be displaying that they're low not blank pressures. They took a second look and are now saying they think I need a sensor they said the right front tire pressure sensor is bad and is effecting the whole system. They want to replace it however I saw somewhere else on this form that someone had the same issue and only needed a stem which I'm assuming is much less than a sensor how can I tell if that is the issue before I spend $195 for a sensor?