How To Tell Which Tire Sensor Is Bad (Exactly!)

Last Updated on July 25, 2021 by Viva Elizeee

Did your tire sensor indicator light up? If it did, one of your tire sensors is in trouble. But how do you tell which one is?

To Tell Which Tire Sensor Is Bad, You Need To:

1. Fill all the tires first.

2. Once every tire is full, start releasing the air one by one.

3. As you release, check your car’s display panel.

The display will show two things if one of the tire sensors is faulty:

  1. An incorrect message
  2. An out-of-range message.

Either way, the tire with the message has a faulty sensor.

Also, you can use a pressure gauge to verify if the sensor is bad. First, get it on Amazon, fix it on the tire valve, and get the pressure reading. Then, compare what you read with what the display shows. If you see any discrepancy, you should know that something’s wrong.

In this article, you’ll know:

1. What TPMS means and how it operates

2. What makes the sensor go bad

3. How to tell if the sensor is bad

4. If AutoZone checks TPMS

5. If you can change only one TPMS sensor 

6. If it’s safe to drive with the TPMS light on

7. And how much it costs to replace the sensor

Now, let’s take each topic down!

Meaning Of TPMS And How It Works

TPMS stands for Tire Pressure Monitoring System. As one of the systems in your car, it tells you when your tires lose air.

The system has a yellow indicator. The indicator shines when your tires are too full in a way that makes your driving unsafe. Like this one:

Before 2007, vehicles did not have TPMS. And at the time, there was a surge in accidents related to underinflated tires. So, something had to happen.

In 2007, the NHTSA focused on underinflated tires in the US. From the study, here is a table capturing some interesting numbers:

Year1999
Cause of AccidentsUnderinflated tires
All Fatalities32,061
Fatalities By Underinflated Tires247
Percentage0.8
All InjuriesAlmost 3,000,000
Injuries By Underinflated Tires23,100
Percentage0.8

But the government could avoid those numbers. So, the US Congress passed the TREAD act. The act requires car manufacturers to include TPMS in their vehicles. The system helps drivers to check the pressure and maintain inflation.

Now, your car either has an indirect or a direct TPMS.

But what are these types? Let’s see.

Indirect TPMS

This system relies on your car’s wheel speed sensors. First, it measures each wheel’s rate of revolution. Then, it uses the rate to calculate the relative wheel size.

If one of the wheels is spinning faster, it means it has less air pressure. So, the system notifies the driver.

So, by ‘indirect,’ we mean that the sensors don’t look at air pressure.

Direct TPMS

Unlike indirect TPMSs, the direct systems use pressure-monitoring sensors in each tire. They help cars to keep tabs on the specific pressure levels. If any discrepancy arises, the indicator illuminates to notify the driver.

What Makes The TPMS Sensor Go Bad?

The sensors are tiny programmable devices found in each tire. Once they pick the air pressure information, they send it to the car’s system.

But that always doesn’t happen.

When the TPMS sensor becomes faulty, it may be because of these reasons:

1. A Recent Tire Change

Did you change your tires the other day? Well, don’t be surprised if your sensor goes bad. Why? You may have broken the TPMS.

But, don’t worry. It’s common for TPMS sensors to break during tire changing. Besides, if you use a tool like a pry bar, you increase the chances of sensor breakage. 

2. Corrosion Inside The Valve System

The TPMS sensor has a valve system that can get rusty. If that happens, your tire sensor won’t detect a flat tire. And that’ll put you in danger.

But you shouldn’t worry if your TPMS sensor has rubber stems. It’s because rubber doesn’t corrode, but aluminum does. So, sensors with aluminum can corrode and cause your tire to deflate.

3. Dead Or Low Batteries On The Sensor

Most sensors are battery-powered. So, their service lives go down with time. And the more often your drive, the more the sensors die down.

Driving in certain conditions drains the sensors more. For example, off-road driving takes more power from the sensors than on-road driving.

Also, driving in constant traffic will take a significant toll on the TPMS.

When the batteries die or go low, your indicator will illuminate. And when that happens, you should change the batteries to fix the issue.

How Do You Know If Your TPMS Sensor Is Bad (Apart From Indicator)?

What if a tire sensor becomes defective, but the indicator doesn’t show? How would you know? We’ll here are other non-indicator symptoms to look out for:

1. Your Tires Will Have Low Air Pressure

You should be checking your tires before you drive – always. And when you notice you have underinflated tires, look at the indicator. If it does not illuminate, the TPMS sensor may not be working. To confirm, you’ll need a tire pressure gauge.

2. Your Steering Wheel Will Be Jerky

If your front tires have little air pressure, handling the wheel won’t be easy. When tires are soft and have low air pressure, your drive won’t be steady and straight.

This symptom is dangerous since it can cause an accident. So, once you can’t handle the wheel, check the TPMS sensor. Something won’t be okay there.

3. Your Vehicle Will Become a Fuel Guzzler

When your tire flattens, its friction against the road increases. That forces the vehicle to need more traction for it to move. Then, the engine will have to burn more fuel to provide more traction.

So, if your fuel is running out quicker than usual, check the sensors. 

Can AutoZone Check TPMS?

AutoZone can refer you to a pro to check TPMS. To use their Shop Referral Program, visit their website and enter your location.

If you see an ‘AutoZone’ mechanic nearby, drive to their location. There, the ‘AutoZone’ mechanic will check your TPMS.

Can I Replace Only One TPMS Sensor?

From a Tacoma forum, it’s okay to replace one TPMS Sensor. So, no need to replace all.

But, when you do, you have to program the new sensor into the car’s ECU. To explain, the vehicle should know that one tire has a new sensor.

And you can do that job in under 5 minutes. But if you can’t, get a dealer to do the reprogramming at $100.

Is It Safe To Keep Driving With The Tire Sensor Light On?

No. When the tire sensor light is on, one of your tires is flat. And if your keep driving, you’ll cause the tire to wear. So, in the end, the tire will fail.

How Much Is To Replace A TPMS?

The average cost of repairing a TPMS sensor is $230, the range being $223 – $237. The parts will cost you $170, while labor will range between $53 and $67.

Conclusion

It’s easy to know a bad tire sensor if you have the tools. So, ensure you get a digital pressure gauge to check your tires’ air pressure. Then, compare the pressure gauge readings to what the display panel reads.

Once you detect a faulty tire sensor, change it immediately. That way, you’ll be safer.

And finally, if the problem seems overwhelming, take your car to an auto shop. The mechanics will know how to take care of the bad tire sensor.

Thanks for reading, and remember, sharing is caring!

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