Join Date: Aug 2016
Location: Chicago, IL, USA, North America, Earth, Sol System, Sector ZZ9 Plural Z Alpha, Milkyway, Universe
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The TPMS in the CX-3 is based off of the ABS system. It watches the wheel speed sensors to see if any of the wheels are turning slightly faster or slower than the others.
When you reset the system, you are telling the system "the pressures are correct, remember these relative rotation rates."
I think the standard for detection is 20% in 20 minutes (or pretty close to that). That is, the system has to warn the driver within 20 minutes if one tire changes by more than 20%.
The annoying side effect of this is that if you drive one tire over a bump under power, and that wheel bounces off the ground, it will spin a bit faster than the rest until it comes back down. Since the system knows that the brake isn't applied, it thinks that one of the tires has gone flat. (Edit: This is just a theory but it would explain why people get TPMS warnings after going over bumps.)
Another side effect of this is the gas laws. Pressures will change roughly 1 psi for every 10F. However, as long as all the tires change at the same rate, the system probably won't know because all of the tires should still have roughly the same rotation speed relative to each other.
If you've reset the TPMS and you're still getting warnings, it's possible that one or more of a few things have happened:
Quit flooring the gas over bumps... (j/k)
There's a problem with one of the tires that nobody has found yet.
User error. I trust you can follow directions but maybe you made a mistake.
Last, I read on here somewhere (but can't find it anymore) that if you try to reset the TPMS more than 2 or 3 times in a single drive, it will assume a system malfunction and only the dealer can reset it after that.
I recommend you get a $10-$20 dial-type tire pressure gauge and leave it in the glove box. I hate the stick type and never trust the ones at the gas stations.
2016 CX-3 GT iAS AWD, Soul Red Metallic on black
2017 MX-5 RF Launch Edition
2005 RX-8 Sport Sunlight Silver under Cone Rash (because racecar!) -- SOLD!
Science adjusts it's views based on what's observed.
Faith is the denial of observation so that belief can be preserved.
Last edited by NotAPreppie; 01-16-2018 at 01:57 PM.