Learn something new every day! Starting in 2014, Honda adopted Indirect TPMS on Civics, eliminating the little monitoring devices inside each wheel. The new indirect method watches relative tire speed across the four wheels using the ABS wheel-speed sensors. If the computer notices a deviation from baseline speed numbers, it gives you a dash light warning to 'check tire pressure'.

The 'baseline' values are established using a reset procedure. In the settings menu, there is an option to calibrate the tire pressure monitor. The idea is you fill all four tires to your desired pressures, and then calibrate. Once you initiate the calibration, the computer then watches actual wheel speeds over 20 - 30 minutes of highway-speed driving to establish and store the baseline numbers.

I'm not sure how sensitive the indirect method is, but something to be aware of is that anytime someone changes tire pressure it could conceivably be noticed by the monitoring system. In my case, I run 35 - 36 psi. If I took the car somewhere and they adjusted the pressure to some other level (say 32 psi), then that might cause the monitoring system to notice a deviation from the baseline and throw a warning light. Since invoking calibration is so quick and easy, it seems like the prudent thing would be to make it a regular practice to recalibrate every time you air up the tires.

 

My 2001 Olds Alero had a system of that nature. It would detect if one tire was about 8 psi below the others.

 

Seems like a better solution than little devices inside each wheel with batteries that will someday poop out.

And, it may help end that annoying practice of tire shops adding a few bucks to your invoice for "TPMS service" when you buy new tires.

 

I do recall that it was only effective for ONE tire being low. If all tires dropped in pressure, you'd never get an indication. The advantage of the TPMS is it's actually based on a set pressure. IIRC, with the Prius it's 28psi.

There are inexpensive ways to get TPMS replaced. You can purchase a set of aftermarket sensors and have them installed with your next tire change for less than $200 total.