When light on your dashboard lights up tire pressure monitoring systems (TPMS), this usually means that the air pressure in one or more tires has dropped below the expected level. The light can also erroneously work due to a bad sensor, it can also turn on and off, apparently at random.

If you have a TPMS indicator, it is important to remember that it is not a substitute for regular maintenance. Although inclusion indicator TPMS can be a great warning before an upcoming emergency, there is no substitute for physically inspecting your tires with a pressure gauge and topping them up as needed.

TPMS indicator appears on the car dashboard
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What does the TPMS light actually mean?

If you have a car with TPMS, that means there is a wireless sensor in every tire. Each sensor sends data to the computer, and the computer turns on the TPMS indicator if any of the sensors indicate a pressure value that is above or below the safe operating range.

While the best answer to turning on a TPMS light is to check your tire pressure with a hand-held gauge, the light can actually convey some pretty important information if you know what to look for.

TPMS indicator lights up while driving

  • Easy Virtue : turns on and stays on.
  • What does this mean : air pressure is low in at least one tire.
  • What should you do : Check the tire pressure with a pressure gauge as soon as possible.
  • You can still drive : Although you can drive with the TPMS light on, be aware that one or more tires may have very low air pressure. Your vehicle may not perform as you expect, and driving with a flat tire may damage it.

TPMS light comes on and off

  • Light Behavior : Lights up and then turns off, seemingly at random.
  • What does this mean : The tire pressure of at least one tire is probably very close to the minimum or maximum rated inflation. When the air is compressed due to cold weather or heated, the sensor is triggered .
  • What should you do : check the tire pressure and adjust it .
  • Can you still ride A: The air pressure is probably close to where it should be, so it’s usually safe to ride. Please be aware that the vehicle may not perform as you expect.

TPMS light flashes before turning on

  • Light behavior : Flashes for a minute or so every time you start the engine and then stays on.
  • What does it mean A: Your TPMS is probably faulty and you can’t count on it.
  • What should you do : Get your vehicle to a qualified technician as soon as possible. In the meantime, check the tire pressure manually.
  • Can you still ride : If you check the air pressure in your tires and it’s OK, then you’re safe. Just don’t count on TPMS to alert you to a problem.

Tire pressure and temperature change

In most cases, your tires will be filled with air that is identical to the atmospheric air. The only real exception is if they are filled with nitrogen, but the same rules of thermodynamics apply to both elemental nitrogen and the mixture of nitrogen, carbon dioxide, oxygen and other elements that make up the air we breathe and pump into tires.

According to the ideal gas law, if the temperature of a given volume of gas decreases, the pressure also decreases. Since the tires on a car are more or less a closed system, this essentially means that when the temperature of the air in the tire goes down, the air pressure in the tire also goes down.

The reverse is also true in that the air pressure in a tire will increase if the air temperature rises. As the gas heats up it expands with nowhere to go as it is stuck in the tire and the pressure builds up.

The exact amount of tire pressure increase or decrease will depend on a number of factors, but a general rule of thumb is that when decrease in ambient temperature the tire may lose approx. 1 lb/sq. inch by 10 degrees Fahrenheit and vice versa get 1 lb/sq. Inch 10 degrees Fahrenheit as the environment warms up.

Cold winter weather and tire pressure monitoring systems

In situations where problem With TPMS only occurs in winter, it is fair to assume that cold temperatures may have something to do with it, especially in areas where winters are exceptionally cold. For example, if a vehicle’s tires were filled to specification when the ambient temperature was 80 degrees and nothing was done when winter arrived and the outside temperature dropped below freezing, this alone could explain the fluctuation in 5 PSI in the tire. pressure.

If you’re having an issue where the TPMS light comes on in the morning but goes off later in the day, or your tire pressure looks normal after a certain amount of driving time, a similar issue may be occurring at work. ,

When you drive, the friction causes the tires to heat up, which also causes the air inside the tires to heat up. This is one of the reasons manufacturers recommend filling tires when they are cold rather than hot from driving. So there’s a very real possibility that your tires could be in spec in the morning and then show up right the same day the mechanic checks them.

Tire pressure check against TPMS light addiction

If you check your tires in the morning before you drive at all and the pressure is not low but the light is still flashing when you drive, then you probably have a bad TPMS sensor. It’s not very common, but it does happen, and some products, such as «fix plane» injectable mixes, can speed up TPMS sensor failure under certain circumstances.

On the other hand, if you find that the pressure is low when the tires are cold, then this is a problem. Filling tires with cold specs when they are really cold will almost certainly get rid of the problem of re-turning TPMS lights on in cold winter weather.

Incidentally, this is also the reason why it is a good idea to check and adjust tire pressure throughout the year. The idea of ​​adding «falling air» or «spring air» to tires may seem like a joke, but accounting for pressure differences due to ambient temperature, as the changing seasons can prevent problems with tire pressure monitoring indicators.

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