My Orange TPMS I got off of RealST is really finicky. In the winter, I have to turn the key all the way to the right to the accessory position, let it sit there for a bit while I start putting on my gear. Once both of the tire pressures show up on the screen, I start the bike. I get an accurate reading of the tire pressures and temperatures cold. Now, as I'm driving, if I see a rise in pressure or temperature in the first few miles, eureka, the sensors are reading correctly. If the pressure stays where it was when cold after a few minutes, I know in exactly 20 minutes after I turned on the bike, I'm going to get either an E1 error or an E2 error. Last summer when I bought the unit, it was hit and miss also, but it was more reliable in the warmer months.
RealST set me new units. Yet to put them on. Will report on them once I install them.