My Tire Pressure Light Keeps Coming On

car tire pressure light

“My Tire Pressure Light Keeps Coming On” is a very common phrase we hear often at Wilton Auto And Tire Center.

We will explore some reasons, that your tire keeps losing air, or my TPMS light is always on.

What is T.P.M.S.?

First, let us understand how your TPMS, or Tire Pressure Monitoring System works. Each vehicle Make, may have a different, yet similar approach, with the common goal to let you know, when one (or more) tires are low on air pressure. Most research claims this is approx.. 25% but we have seen TPMS lights illuminate, with tires simply being 3-4lbs low, which can be as low as a 10% margin! Whatever the built in “spec” is, which will vary from a Chevrolet to an Audi, or a BMW, the Tire pressure Light is made to illuminate, to let you know you have a tire that needs attention.

How Does TPMS Work?

The most common TPMS system involves having a sensor, built into your tire valve, which sends out a radio frequency, interpreted by an on board computer as tire pressure. Another style is utilizing your ABS, or Anti Lock Brake System, where the on board computer reads the revolutions of each tire, comparing to each other, to determine the difference in circumference, which leads to a low tire pressure. This system has gained in popularity, as the technology gets better each model year.

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Why does my TPMS light go on so often?

The most common cause of your TPMS light illuminating often, is your tires NEED AIR! As much as we like to blame things on “the light” we should never ignore the fact that we need to put air or check the air in our tires at least once a month. You could also have a faulty sensor, or sensors. What most people do not know, there is a battery as part of your sensor, which will fail ultimately similar to your Key Fob, or watch battery. We have found typically after 4 or 5 years, they start to fail. We then recommend replacing all of your sensors, so you do not “chase” bad sensors for the coming months. Of course, simply sometimes you have a slow leak, a nail in your tire, a bead leak etc. which can be expertly repaired at Wilton Auto and Tire Center. Remember, 1- 2 p.s.i per month loss is normal and acceptable. This may accelerate a bit in cold weather.

Why does my light come on more often when it is cold?

So lets say your Manufacturer recommends 35 psi, and you are at 31 psi. This is not optimal, but also NOT detrimental. Tonight the temperature drops from 50F to 25F ( tire pressure can decrease 1psi for every 10 degrees roughly) so now when you start your car, you have 29 psi (again not detrimental) but ENOUGH to turn your TPMS light on. Some, simply blame the cold weather, but the true culprit is you are actually low on air pressure. So, check your pressures once a month, and top off ALL of your tires if the TPMS light comes on

Tire and TPMS best practices:

  • Check your tire pressures at least once a month
  • Adjust to Manufacturers recommended pressure (listed typically on the driver’s door jamb)
  • If one or more tires lose more than 3-5 psi per month (or sooner) this indicates a problem, and you should
  • have your tire inspected for leaks, and repaired properly
  • When your TPMS light illuminates, as soon as safely possible, visually inspect your tire to make certain you
  • can continue to drive. Then, proceed to the closest air tower and inflate all of your tires
  • NEVER drive on an underinflated tire, as tire damage may occur, as well as your personal safety may
  • become compromised


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Written by Wilton Auto and Tire Center