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Each tire in your car comes with a sensor. If you notice that one sensor is not working as it should, you need to know how to tell which tire sensor is bad.

Your tire sensor, also known as a tire pressure monitoring system, is a small pressure sensor placed in each tire to alert the driver of under or over-inflated tires. In 2007, the NHTSA mandated that all tires have these to reduce mortality rates. However, like every technology, they can fail as well.

If one of your tire sensors fails, the quickest way to root out the bad one is to use a pressure gauge to determine the pressure of each tire. You can also use a TPMS scan tool to diagnose the issue or use the trial-and-error method of releasing air from each tire.

In this guide, we can help you find out the symptoms of bad tire sensors and how to tell which tire sensor is bad. We will also find out what are the causes that result in false readings from the sensors or make it faulty.

As a person who has been driving a car for decades, I have become accustomed to the many vagaries of automobiles and have experienced bad tire sensors myself several times. As such, I can tell you in detail how I handled the situation.

Table of Contents

How Do You Find Which Tire Sensor is Faulty?

Finding faulty tire sensors is a simple process. There are various ways you can figure out which tire sensor is bad.

Car Dash Panel

The most obvious way to find out if there is something wrong with tire sensors is to check the dashboard display panel in your car. It displays the TPMS indicator which is designed like a stylized U with an exclamation mark in the middle.

If you see that the TPMS light is blinking, it is a sign that there is some issue with your tire sensors. The engine control module which collects all the sensor data on your car will trigger a warning on your display panel which will let you know something is wrong with the car sensors.

Digital Pressure Gauge

Another very easy way to determine whether a TPMS sensor is faulty is to use a pressure gauge to check the air pressure in the tires. Note down the readings on the gauge and then compare them to the TPMS readings on the car dashboard.

If you see a difference in one of the readings, it means that the tire pressure sensor is faulty.

TPMS Diagnostic Tool

Using a TPMS diagnostic tool is also another very easy way to find out which tire pressure sensor is not working. This tool is very useful in identifying problems with your TPMS sensor, including a drained battery, wiring issues, or problems with the voltage.

If the air is leaking out of the tire or coming into the tire, the tire sensor will send a signal to the TPMS which will result in a horn chirp. This is a sign of a well-functioning sensor. However, if there is no chirp when the air comes out or goes into the tire, it means that there is an issue with the sensor.

Air Filling and Releasing

Although it is also a good way to find whether your TPMS is working fine or not, it can be a bit tiresome since it requires you to fill each tire with the recommended air pressure and then release the air — and then refill them again so that you can drive your car.

Fill the tires with air and then slowly release it, one tire at a time. Then check the car’s display panel to see if the warning light is blinking each time. If you do not see an alert when releasing the air from the tire, it means the tire pressure sensor in that tire is defective and needs to be replaced.

Once you have identified which tire it is, mark that tire and make sure to fill it up with the right amount of air before you have had a chance to get the sensor fixed. Also, fill the rest of your tires with the right air pressure before you take out your car.

What are the Symptoms of a Defective Tire Sensor?

If a TPMS develops a fault, you will be able to detect several noticeable changes in your vehicles. Some of the ways you can recognize a defective tire sensor are:

Low Tire Pressure

The main function of the tire sensor is to warn you if your tire is low on air. So if you notice that your tire does not have enough pressure or that they have gone flat and you did not see a warning light on the dashboard, it means that the TPMS failed to send a signal to your car’s ECU.

Unsteady Steering Wheel

If one or both of your front tires are low on air pressure, their sides will become soft and flat which will make it difficult for you to keep your steering wheel straight and steady.

If you are experiencing a jerky steering wheel, it might be due to underinflated tire. And if the TPMS indicator fails to light up, it means there is something wrong with your tire sensor.

Fuel Consumption

When your tire is leaking air, the friction between the ground and the tires increases, which means the car engine has to exert more effort to keep you moving. This makes it burn up more fuel and you will see your fuel consumption increase significantly.

If you cannot detect any obvious reasons why your car is burning fuel excessively, it is worth your while to check the tire air pressure and see if the tire sensor has developed a fault.

ABS Light Warning

Your car’s anti-lock braking system ensures good road traction by preventing your wheels from locking up and skidding on wet or slippery surfaces. However, if any of your tires have low air pressure, your car’s ECU will sense abnormal speed and it will send an inaccurate signal to your ABS which will light up the warning signals in the dash.

Hence, if your ABS lights up for no apparent reason, it is a good idea to check your air pressure and TPMS.

Inaccurate Warnings

If your TPMS is not working as it should, you might get strange warnings on your DIC. It could indicate that you have an underinflated tire even if your tire has the perfect air pressure. If you get these warnings, it is important to get them checked out and see if your tire sensor is working accurately or not. It may be because your TPMS requires a reset or if its batteries have failed.

What Causes Your Tire Sensors to Go Bad?

The main cause of a faulty tire pressure monitoring system is a defective tire sensor. So what are the things that can make your tire sensor go bad?

Dead Batteries

Your tire sensors are equipped with batteries that have a lifespan of anywhere from five to 10 years. The life of the tire sensor’s battery can vary depending on how frequently you drive your car. If you drive your vehicle very frequently, your sensors will be used more and will drain the batteries faster.

In addition, the temperature and traffic conditions also have an impact on the life of a tire sensor’s batteries. If you live in a state that has hot summers, it can put a lot of strain on the sensor battery as compared to if you live in more temperate regions.

Moreover, if you experience a lot of traffic jams regularly, they can also take a toll on the tire sensor’s battery as opposed to when you are driving at a constant speed on open highways.

If the battery is low or drained, it might set off malfunction warning signals which will turn on the TPMS light. To fix this problem, you will need to change the sensors in the tires.

Corrosion or Debris

Any rust or corrosion on or inside the valve of the TPMS can cause the sensors to malfunction. If you do not fix this issue quickly, it can lead to serious problems for your car, like puncturing your tire when the corroded valve stem snaps.

This issue, however, is only limited to tire sensors that are equipped with aluminum valve stems and not rubber ones.

In the same way, debris and dirt accumulation can also cause the sensors to stop working properly.

Cold Weather

Like hot weather, cold weather can also result in inaccurate readings. This is because the cold can compress the air in the tire, which can mess up the readings. However, keep in mind that this does not mean that your TPMS is irrevocably damaged.

If you live in colder states, it is a good idea to let your car run three or four miles, give them a chance to heat up the air inside, and then check the reading of the TPMS.

Can Changing Tires Make Your Tire Sensors Go Bad?

Yes, as strange as it may seem. If you have recently got your tire changed, it could be that you damaged the tire sensors when removing the tire aggressively with a tool like a pry bar. This is because a lot of the equipment used to change a car’s tire was not designed to plan for the eventual installation of the TPMS in the tires. During a tire change, the TPMS installed on the rim can get snagged by the tire and become damaged.

Fortunately, there is a way you can prevent your TPMS from being damaged during a tire change:

  • It is best to use an aluminum clamp-in tire valve stem to remove the nut from the stem and wait until the sensor has fallen safely into the tire. This is the simplest way to prevent damage to your sensor.
  • For a rubber stem, make sure your valve is positioned at 90 degrees when you break the bead on both the front and back of the tire. This will prevent the tire sensor from being crushed.
  • Make sure the valve is positioned under the dismount head when you start the turntable to change the tire. This will prevent the tire from hitting the valve and damaging the sensor.

What is the Cost of Replacing a Tire Sensor?

Typically, a tire sensor can cost you anywhere between $50 and $250. If you think that the tire sensors in all four of your tires have gone bad, you can expect to pay between $200 and $1000 for buying the sensors. If you do not know how to replace the tire sensors yourself, you can get them installed by any car workshop for about $10 to $30 for each tire. This will bring your total cost to about $240 to $1,120.

As you can see, this is not an unsubstantial sum so it is a good idea to check the car mechanics in your area to make sure they can do the job adequately. Not every mechanic is experienced or even a mechanic and if you go for dirt-cheap service, there is a high chance your TPMS may not be properly installed or become damaged in the process.

This can lead to serious issues with your car’s tires as well as put you at a higher risk of road accidents. Therefore, only enlist the services of a certified and experienced mechanic, even if they charge you a bit more since they will get the job done the right way.

Also, keep in mind that you need to reset the TPMS light every time you get the sensor changed.

Is It Important to Know Whether Your Tire Sensor Has Gone Bad?

The TPMS has made it easier for drivers to perform tire maintenance. The TPMS system has been designed to monitor the air pressure in the tires and to notify them in case anything goes wrong. All in all, the system has added another level of safety to driving by ensuring you do not suffer from a tire blowout that can lead to terrible road accidents.

That is why it is important to ensure your tire sensors are working properly and keep a watch for the various symptoms of faulty TPMS. If you do notice something amiss with the sensors, it is best to get them checked out rather than risking your safety on the road.

How to Tell Which Tire Sensor is Bad

About The Author

Charles Redding

Charles Redding

I've spent many years selling cars, working with auto detailers, mechanics, dealership service teams, quoting and researching car insurance, modding my own cars, and much more.

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