What Is TPMS and How Does It Work? What to do when TPMS light comes on?


Your vehicle is loaded with sensors in various places of the structure to ensure the safety of the passengers. One way your vehicle keeps you safe every time you drive is by utilizing the TPMS. This system continuously monitors the most important safety systems: your tires and your brakes.

What is TPMS?

The Tire Pressure Monitor System or TPMS is an electronic system in your vehicle that alerts the driver when the air level of the tires is low.

2 different types of sensors (e.g. speed sensor) work together to send signals to the computer when there is a problem with your tires.

This is especially concerning when the tire pressure is severely-underinflated leading to very unsafe driving conditions.

In order to monitor safe driving conditions in your car, the tire pressure monitoring system is implemented into all modern vehicle makes and models.

Why is TPMS in place?

TPMS is in place in most vehicles after 2006 to ensure drivers understand the safety importance of monitoring and regulating the tire pressure on their vehicles.

To make sure people understood these safety procedures, Congress passed the TREAD-act, which stated all cars after 2006 must be equipped with TPMS.

Direct and Indirect TPMS

To fully understand TPMS, you need to know the two different types of systems Direct TPMS vs Indirect TPMS.

Direct TPMS

direct tmps

First, there is Direct TPMS, this system uses a sensor that is located within the wheel itself to monitor the air pressure in the tire.

In the event that your tires air pressure falls below the manufacturers recommended level. 25%, the sensor will send this information to the computer system.

Wireless receivers within the dashboard of the vehicle should transmit this information and illuminate the TPMS indicator light.

In some cases with Direct TPMS, there is a sensor for tire temperature readings.

This is a particularly helpful sensor so that you know if the TPMS light is illuminated due to change of temperature.

Indirect TPMS

The other system is Indirect TPMS, this service works with the speed of the tires and the anti-lock brake system.

Indirect TPMS is a very low maintenance system that requires less upkeep and less expense than Direct TPMS.

The sensors that monitor the wheel speed measure how fast the tires turn. If the air pressure is low in one tire, this tire will rotate at a different speed.

If the sensors indicate that a tire is rotating faster than expected, the systems within the vehicle’s computer will alert the driver.

For this reason, it is called Indirect TPMS. Because it does not actually monitor the pressure inside the tire, but instead the rate of rotation.

Benefits of TPMS

There are a multitude of benefits when it comes to TPMS. But by far the most important benefit is keeping the driver safe by maintaining safe conditions

TPMS is an alert system that will tell you if the pressure in your tires is low or you are on the verge of deflation.

In other words, your vehicle will monitor safe driving conditions by helping to improve the way the car handles.

You will also notice a decrease in the wear of your tires thanks to TPMS.

Additionally, another benefit from TPMS is reducing the distance of braking whenever you press on the brakes, if your tires are properly inflated, there is less skid from your vehicle.

Tire Pressure Monitoring System: How it Works

The Tire Pressure Monitoring System within your vehicle works through wireless communication between the computer and the tires.

Advanced sensors inside the tire can indicate the exact pressure and send this information to the vehicles control panel to inform the driver.

That means, if a piece of debris or a nail penetrates the tire and air begins to leak, the sensors will immediately tell the driver a problem has occurred.

It doesn’t just stop there, additional sensors in the brakes of your vehicle continuously monitor how fast or slow your tires are rotating.

If a tire is losing pressure, it may rotate at a faster speed than the other tires.

An enhanced rotational speed will be picked up by the Indirect TPMS sensors. Then they send this signal to the TPMS indicator.

With these two pieces of information from the tires, the computer within your vehicle can read and deliver messages to the driver that the tires need assistance.

Why does TPMS light come on?

The TPMS light should only be illuminated in the event that the air pressure within the tire falls below the recommended level, normally this is 25%.

This indicator light could have a variety of meanings. For example, there may be a hole in the tire causing a loss of pressure, or a change in environment.

However, it is not recommended to run to the air pump right away.

Often times, a change in weather can cause a difference in air pressure. Therefore you may notice an illuminated light on a, particularly cold morning.

It is suggested to wait to make sure the indicator light stays illuminated before inflating or changing the tires.

BONUS: Top 10 TPMS Reset Tools to Monitor Your Vehicles Tire Health 2021 

What to do when TPMS light is on?

In the event that your TPMS light turns on, as I said previously, it is not advised to run straight to the air pump.

Instead, first, inspect your tires.

The TPMS indicator will more than likely let you know which tire is low in pressure.

Inspect your tires to see if any seem deflated or punctured by an external element such as a nail or glass.

If a tire seems low in pressure, look at the manufacturer recommended inflation pressure. This can usually be found on the tire.

Inflate the tire to the desired pressure, and when it is inflated the TPMS light should turn off.

If there is a further problem, the tire might need to be changed.

If this occurs, you can bring your vehicle into any tire repair shop. Here, you should have them run the necessary tests to monitor and replace the tire on your vehicle.

After a replacement or tire repair, the TPMS light should turn off.

Read more: 10 Best OBD2 Scanners with ABS and SRS Review & Comparison 2021

How to Reset Your Low Tire Pressure Light

Your vehicle’s low tire pressure light, also called the “TPMS” light, is an important safety feature. Not only do low tires cause your car to get poor gas mileage, but they also reduce your traction.how to reset your low tire pressure light

So, let’s take a closer look at how to reset a low-pressure light.

Sometimes you may think, like all things mechanical and electrical, your vehicle’s safety lights aren’t perfect. Occasionally, things go sideways, and you end up with a lit TPMS light when your tires are fully inflated. In these cases, it’s important to know how to reset your low tire pressure light. Here’s how it’s done.

So, how do you reset a low tire pressure light? Here are four quick, easy ways you can do the job at home, without the need to visit your mechanic. We’ve listed these methods in order of difficulty, from easiest to hardest.

Drive at 50 MPH for 10 minutes

Your vehicle’s computer re-scans its sensors periodically. If you’ve just topped up and verified that your tires are full, try driving for 10 minutes. Since many cars require you to reach a minimum speed before they run a scan, we recommend driving at least 50 MPH. Use cruise control to maintain speed if you’re having trouble.

Use the TPMS Reset Button

Most cars have a reset button that will clear your TPMS light. It’s usually located under the steering wheel. If you can’t find it, check your owner’s manual.

Next, with the vehicle off and parked, turn the key to the “on” position, but don’t start the car. With the key in this position, hold the TPMS button down. Keep holding it until the TPMS light blinks three times. Then start your car and let it idle. Within 20 minutes, your light should go off.

Disconnect and Reconnect Your Battery

If you’ve tried these methods and your low tire pressure light is still lit, there may be a glitch in your car’s computer. Oftentimes, these glitches can be fixed simply by doing a hard reboot on the computer. But don’t worry. You don’t need to be an automotive genius to do this job. You just need a wrench.

With the car off, open your hood. Locate the battery, and use the wrench to disconnect the cable from the negative terminal. Then, turn your vehicle on. Hold the horn down for about three seconds to drain any residual power from your electrical system. Turn the car off, reconnect the cable, and you’re good to go.

Deflate and Reinflate Your Tires

Sometimes, your sensors just get stuck, and you need to drastically change the tire pressure to jog their memory. To do this, inflate all your tires to 3 PSI above normal inflation, then deflate them completely. Reinflate all tires to their recommended level.

Make sure to include your spare tire in this process. Many vehicles also have a sensor in the spare.

Other Possibilities

If you’ve tried all the above tips and your light is still stubbornly shining, you may have a damaged sensor. Sensors can sometimes become damaged during normal automotive work, like brake jobs and tire rotations.

If you’ve recently been to a mechanic, take your car back to the same shop and see what they can do.

Sometimes, a TPMS light may indicate that a tire has a slow leak. You inflate the tire and everything looks fine, but your pressure is low again in short order. In this case, a mechanic can identify the leak and patch or replace your tire.

Another possibility is that your air pressure gauge needs to be calibrated, or has a dead battery. These jobs require special equipment, but they only take a few minutes. A mechanic can get you taken care of in less time than an oil change.

In rare cases, you might have a wiring short or other electrical issues that cause the sensor not to register. Once again, you’re going to need a mechanic.

Finally, your car may have an indirect tire management system. In this case, you’ll need to – you guessed it! – visit a mechanic to have your wheel sensor checked. One clue that you’re dealing with this problem is your ABS light. In an indirect system, this light will also illuminate if your wheel sensor fails.

A Flashing TPMS Light

One thing we didn’t address is what to do if your TPMS light is blinking. In most cars, this is a warning that your tire sensor batteries are low and need to be replaced. Check your owner’s manual to be certain. But either way, you’re going to need to visit a mechanic to have this done.

Bonus: Top 10 TPMS Reset Tools to Monitor Your Vehicles Tire Health 2021

Caring For Your Sensors

As the old saying goes, an ounce of prevention is worth a pound of cure. To avoid having to go through all this hassle again, it’s important to treat your sensors properly. The better you treat them, the less likely they are to fail you. Here are a few ways to do exactly that:

  • Keep your cap screwed onto the valve stem. It’s not just there for decoration. It keeps water, road salt, dirt, and other debris out of your tire. All of these things can damage your sensor.
  • Use quality valve stems. Brass cores corrode, and corrosion-resistant stainless steel cores only cost a few dollars more. Considering the cost of replacing a tire sensor, this is a no-brainer.
  • Finally, don’t use the flat repair compound that comes in an aerosol can. Even sensor safe flat repair compounds can plug the sensor’s hole. Since the sensor needs this hole open to properly measure the air pressure, plugging the hole causes it to fail.

Bottom Line

Remember: whether your low tire pressure light is illuminated, you may have a serious safety issue. Of course, in all probability, it’s probably nothing. But if you’ve verified that your tires are inflated, it’s important to know what’s causing the warning.

We hope these helpful tips and tricks have helped you sort out your TPMS light issues. And if you found a serious problem, we’re glad we helped you find it.


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