Almost every late model car has a TPMS-tire pressure monitoring system.  They are designed to monitor the tire pressure of each tire on the car—and some monitor the spare tire as well.  

Why is that important?  Let’s start with over-inflation.  An over inflated tire can cause increased tire wear and a rough ride.  Over-inflation will also cause a tire to wear quickly in the center of the tread.  Under inflated tires on the other hand, will cause handling issues, increased tire temperature, decreased fuel economy and wear on the outer edges of the tire.

What to do if the TPMS light comes on?  The first and easiest thing to do is check your tires’ pressures—including the spare.  DO NOT use the tire pressure printed on the tire.  The correct pressure is listed in the car’s door jamb, gas flap or owner’s manual.  Remember, tire pressure fluctuates with temperature.  So if cold weather suddenly arrived and your TPMS light came on…that could be why.

What if the tire pressures are correct but the light stays on?  Now it’s time to let a professional take a look.  It could be that you have a bad sensor or sensors.  Each tire has a sensor (and maybe the spare), and each sensor is battery powered.  The most likely culprit is a dead battery in the sensor.  Unfortunately the battery can not be replaced.  New sensors require removing the tire from the rim, installing the new sensor, and reprogramming the computer in your vehicle to recognize the new sensor.

Obviously there could be other problems.  For example:  control modules, wiring issues, etc.  The most common, however, reasons for the light to come on are tire pressure and bad sensors.

Other considerations:  Never let the TPMS take the place of regular tire tread and pressure checks.  On some makes and models, tire rotations will cause issues since the vehicle’s computer no longer knows where each pressure sensor is located.  Most shops will check for this and correct the locations after rotation.  Typically a sensor battery last 7-10 years so if your car is approaching that benchmark and you need tires…that might be the time to install new sensors during the new tire mounting and balancing.