On your dashboard, there’s an exclamation mark in the middle of a horse shoe-shaped warning light. This is the tire pressure light. It’s also called the TPMS warning light.

The acronym TPMS stands for Tire Pressure Monitoring System. This system is found in all modern passenger cars. It consists of sensors mounted on each tire and connected to a computer. The computer will turn on the warning light when the pressure in one or more tires is too low.

What does it mean to you as a driver? What does the tire pressure warning light mean, and what should you do when it comes on?

Tire Pressure Basics

Let’s talk about tire inflation before we discuss the TPMS.

Every day, even tires that are working properly lose a tiny amount of air. This tiny amount accumulates over time and causes your tire pressure to drop. Temperature also affects tire pressure. The pressure drops by one pound per square inch for every 10 degrees Fahrenheit drop in temperature. Pressure will increase for every 10 degrees temperature rise.

Fill your tires up on a sunny, 80-degree day. You will be 2 PSI underinflated two months later when the temperature is 60 degrees. You’ll still be underinflated by 2 PSI a few months later when the temperature drops to 30 degrees.

Why is this important? Here are some reasons why:

  • Underinflated tires wear out faster. The tire will become squishier as the pressure drops, and the rubber is more exposed. The more this happens, the faster the tire edges will wear out, resulting in a premature blowout.
  • You will also experience less traction. You won’t be able to control your vehicle in the rain, when it snows, or other adverse weather conditions. Even if you are an experienced snow driver, you may find yourself sliding and skidding around the road.
  • Low fuel mileage will be reduced by poor inflation. The flabby tire makes it more difficult to turn the wheel, which means that each turn of the wheel requires more energy.

Overinflated tires can also be dangerous. It’s not always important to have the maximum pressure. It’s important to use the right pressure for your vehicle and tires.

What does the TPMS light mean?

The TPMS light is a simple indicator that the tire pressure in your car is either too low or high. There are also a few things you should be aware of. It’s not unusual for all or most of your dashboard lights to come on when you turn the engine on. The TPMS light will turn on along with other lights and then go off.

When the TPMS light illuminates, you may encounter the following:

  • If the TPMS light stays on, then at least one tire’s pressure is either too low or high. It’s worthwhile to check your tire for slow leaks if this occurs frequently. Stop at an air compressor service station as soon as possible and adjust the tire pressure as necessary.
  • The TPMS lights will flash intermittently. Typically, this happens when tire pressure is borderline. Imagine you are waking up to 40-degree weather and that your tire pressure is two PSI below the recommended level. The TPMS light comes on as you drive to work. It’s 60 degrees when you leave the office. The TPMS light has now gone off. It may turn off even mid-drive as friction heats your tires.
  • If the TPMS light blinks and then remains illuminated, it means that something is wrong with your system. The computer, a faulty cable, or an individual sensor could be to blame. Take it to an auto mechanic to have the problem diagnosed.

Do I still need to do manual pressure checks?

The TPMS light is an excellent tool, but still only a tool. Before making any tire adjustments, you should always check your tire pressure manually. It’s also a good idea to check the pressure of your tires regularly, even when the warning light does not come on. This is for a number of reasons:

  • It may be that the sensor is defective and does not detect any pressure drop.
  • The TPMS system can be incorrectly calibrated for the vehicle weight when hauling or towing.
  • The light is a warning. The light does not tell you what tire is under-inflated, if it’s a mixture of tires, or if the pressure is too high or low.

It’s important to learn how to manually check tire pressure.

How do I manually check my tire pressure?

You can buy a tire gauge for a few bucks at any auto shop. The correct pressure must also be known. The figure will be on a sticker inside the driver-side door jamb. You can also find it in the owner’s guide.

If necessary, add or drain air to get the right pressure. Don’t worry if you see the TPMS warning light. It can take the computer up to 200 miles before it resets and turns off the light.


It’s important to always follow up on the tire pressure indicator light. You’ll enjoy a more fuel-efficient and safer driving experience by performing regular manual checks on your tires.