This sensor came on, I filled the tires up to 35 and it went away. A few weeks later, I decided to air the fronts to 40 and the backs to 38 PSI. The light came back on. I put the car into ON and held down the TPS Set button above my right knee, the light WOULD NOT blink. It's almost as if the set button doesn't function. Or could it be one of the sensors itself? This is a Gen 2 so I assume the spare does not have a sensor. I even deflated all tires back to 35 PSI and tried holding down the Set button, but still to no avail. Any ideas?
Do your wheels still have the original factory sensors? If so, they are 7-8 years old and may be running into battery wearout. But this isn't the only possible culprit, and I don't yet know enough about TPMS to guide you to the most likely ones.
Agreed. Our 2006 Prius (so Gen 2) owner's manual expressly says so. On the other hand--completely apart from debugging your current concern, you might be well advised to top up the spare pressure. I went through a TPMS alert debugging a few weeks ago, and on my way to finding that my problem was just that the onset of cold weather had dropped the pressures just below the alarm point (which I had deliberately set high to get earlier warning), I realized that neither the dealer nor I had pumped the spare for years, and it was sitting at about half spec pressure (which is prominently displayed on the sidewall, and is much higher than for the regulars.). I suspected batteries on our TPMS alert, but it turned out they were still holding up. So noticing and addressing my spare pressure was just a happy accident of the situation.
They are the orginal sensors But yea it is just weird that they DID work just weeks before, and inflating them higher than they originally were triggered the warning light again. So I suppose if one or more of the sensors is not working properly, this is the cause for the TPMS set button under the dash to be ignored?
Aging and weak batteries are more likely to fail as weather cools, and we've had many cases of 12V battery problems in the past few weeks. It wouldn't be surprising to have TPMS batteries going at the same time, and just coincidentally be noticed while doing other things. This is where I cannot answer, due to lack of experience. Others need to chime in here.
You say you put the car into ON. In order to reset the tire pressure warning system, the car needs to be in IG-ON; that is, the Ready light must not be on. You get into IG-ON by keeping your foot OFF the brake, then pressing the Power button two times.
