I recently had my wheels powdercoated and I have to buy new valve stems since the last ones apparently broke. Whenever I was looking for new ones to purchase I had forgotten about the TPMS sensors. So I called the guy that powdercoated my wheel and he said that there were none when he removed the valve stems. Does a 2014 mazda3 sGT come with sensors? If he was right and there were none then why did I never have the low tire pressure light on in my car? I am a bit confused on this.