I recently picked up 2013 Prius V and I went to check the tire pressures preparing for a road trip and noticed 3 of the tires were at proper pressure(36psi I think) but one was at 55psi(max sidewall is 50psi) so I lowered the pressure and reset the system with the button. That said the light came on when I lowered the pressure and the reset doesnt seem to fix the light. I added pressure until I saw the light turn off and it seems around 52 psi is where it needs to be for the light to stay off. The PO did have two new front tires installed before sale so I think the shop must have aired it up until light went out and didnt reset or they ran into same issue as me. This is where the switch is supposed to recalibrate the warning light right? I set it all to correct pressure then do the reset procedure(ignition on hold button until 3 flashes). Is it possible the sensor is just going bad? It seems like all my cars have these TPMS systems fail so I'm used to just checking pressures myself, it would just be nice for my wife to not think about it.
It's best to trust your gauge. But, if you can have another gauge to check it with then you'll know if it's accurate, or close. At 10 years old the batteries in the monitors could be dieing...
Thats what I was thinking, maybe the low battery is sending out a weak signal so until its overfilled it doesnt send a good signal, not sure if thats how it works though. Ive checked it against 2 separate gages(one on a compressor and a $50 automotive one for racing) and I always have good gauges as I race bikes so I keep gauges accurate to 0.5psi so I trust my readings. Ill just live with it until I need new tires.
