6 Reasons The Tire Pressure Light Is on With Inflated Tires

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We all know that tire pressure signal that turns on to let you know that your tire is flat. But, it’s frustrating when this light keeps turning on even when your tires are fine. 

So what do you do when this happens? 

Don’t stress. I’m here to help. 

In this post, I will go over the common reasons why your tire pressure light can turn on falsely and what you can do about it. 

Let’s get started. 

What is Tire Pressure Monitoring System (TPMS)?

The Tire pressure monitoring system or the TPMS will trigger your tire pressure light to turn on. The TPMS will turn on any time it senses that your tire pressure is low. The TPMS is a safety feature on cars that ensures people are driving with adequately inflated tires.

In 2000 congress passed the TREAD Act that made TPMS systems mandatory on all cars manufactured after 2006. This was in response to a firestone tire recall that was responsible for 100 deaths. The act made the TPMS a standard feature on all cars.

Today the law requires that the TPMS must alert you when your tire pressure has fallen more than 25% from the recommended tire pressure. In many cases, car manufacturers use different standards, which may notify you much sooner than a 25% drop in tire pressure.

How does Tire Pressure Monitor Sensor Work?

The TPMS has a simple job, to alert you when your tire pressure is low. The way it does this will vary on the type of TPMS your vehicle has. There are two types of tire pressure monitoring systems: 

  1. Direct TPMS
  2. Indirect TPMS

1. Direct TPMS

Most vehicles use a direct TMPS and most people are familiar with how a direct TPMS works. With a direct TPMS, your car is equipped with sensors at each tire. These sensors read the tire pressure of each tire independently and in real-time. If the tire pressure on any of your tires falls below a specific threshold your tire pressure light will turn on. 

Direct TPMS are more accurate and will detect low tire pressure immediately. This is one major advantage of a direct TPMS. 

2. Indirect TPS

An indirect TPMS operates slightly differently than a direct TPMS. With the indirect TPMS, there are no sensors.

This system monitors and tracks your tire pressure using your car’s ABS or Antilock Braking System.

With an indirect TPMS, your vehicle’s computer will determine the air pressure in your tires based on the rotation of your tires. Using the ABS system monitors the RPM of each tire. If your computer detects anomalies of differences in the RPM of your tires, this will trigger your tire pressure light to turn on.

An indirect TPMS system relies on calculations and assumptions rather than actual measurements. A tire with low pressure will rotate differently than a tire that has the correct amount of pressure.

Indirect TPMS systems don’t track tire pressure in real-time. This makes them less accurate and causes them to detect changes in tire pressure much slower than a direct TPMS. Another disadvantage is that most indirect TPMS systems require calibration after a change in tire pressure or any changing of your tires. As a result, this can leave the safety measure prone to human error which shouldn’t be the case for such as crucial safety feature.

The advantage of an indirect system is that it’s more cost-effective and durable. You are unlikely to have issues with your TPMS system if it’s an indirect system unless there is an issue with your ABS.

How to Know if the Tire Pressure Warning Light is On?

When your tire pressure is low, your TPMS will trigger the low tire pressure light. The low-pressure light is located on your dashboard and will typically flash yellow or remain on permanently.

The tire pressure light looks like a tire or horseshoe with an exclamation mark in the middle. If you see this light or a version that looks similar, you should check your tire pressure.

If your tire pressure turn-on temporarily when you start your car, this is normal. Most dashboard lights will turn on when you start your car.

Likewise, if your tire pressure light turns on and then turns off for some time, it is likely that there is an issue with your TPMS system. If you have an indirect system, you may need to calibrate your system. With a direct system, there may be issues with your sensor or your computer that are causing your light to turn on and off.

In most cases, if there is an issue with your tire pressure, the light will remain on until you fix all the tire pressure issues. If your tire pressure light does turn on you should check immediately to avoid driving on tire pressure that is deflated and unsafe.

Causes of Tire Pressure Light Turning On But The Tires Are Fine

1. TPMS Needs To Be Calibrated

If your tire pressure light keeps turning on, but your tires are fine, then it is possible that you need to calibrate your TPMS. This only applies if you have an indirect TPM system. Since indirect TPMS systems rely on calculations using your ABS, it needs to be calibrated after certain events. 

Some common actions that typically require you to recalibrate your TPMS include: 

  • Changing your tire 
  • Rotating tires 
  • Repairing ABS system 
  • Chaing air pressure 
  • Replacing a tire

Recalibrating the TPMS system is typically not difficult. In newer vehicles, it can typically be done using the main touch screen display. For older cars, there is typically a TPMS button located near the steering wheel or process that you need to follow to reset the TPMS. 

2. Faulty Sensor

This is one of the most common reasons that you might be receiving an incorrect low tire pressure light. You will only have this issue with direct TPMS since indirect TMPS don’t use sensors.

Since direct TMPS are more common, there is a high chance that this is the reason behind your false low tire pressure light.

Tire pressure sensors can begin to fail to cause it to give a faulty reading. Your tire pressure sensor might begin to fail due to wear and tear direct damage, or erratic driving conditions.

To check the condition of your sensor, you can use a TPMS sensor. This tool will scan your sensor and determine if it’s working properly. You can also simply test your tire pressure using a manual tool or install a secondary tire pressure sensor. There are many different options that you can find online. If your tire pressure passes the test with a manual or secondary sensor, then it’s likely that your sensor is faulty and causing an inaccurate reading.

If this is the case, you should take your vehicle to a professional mechanic for inspection. Removing the tire pressure sensor is not an easy job and should only be completed by professionals or enthusiasts with repair experience and the proper tools.

3. Cold Weather

If you live in an area that experiences extremely cold weather, this can also cause an inaccurate tire pressure reading. In cold temperatures, air molecules tend to shrink. As a result, this can cause your tire pressure to turn on.

In most cases, as you begin driving and your car and tires begin to heat up, the tire pressure light should turn off. If your tire pressure does not turn off after driving for 5-10 miles, you should check your tire pressure.

4. Tire Pressure Sensor Battery Issues

Another common issue that can cause an inaccurate tire pressure reading is a dead tire pressure sensor battery. Tire pressure sensor batteries only have a lifespan of 5-10 years. In some cases, harsh weather conditions or damage to the battery can shorten the lifespan of your battery.

If you test your tire pressure sensors and they are coming back as functional, you should have a professional mechanic inspect your sensor batteries. Sensor batteries are inexpensive and relatively easy to repair.

5. Faulty or Damaged Wiring

Another common issue that can result in a false tire pressure warning light is faulty or damaged wiring.

You will likely see this on the wires that connect to the tire pressure sensors. If these wires are damaged or corroded, it will cause your TPMS system to malfunction.

This issue is often confused with a dying battery or faulty tire pressure sensors since they cause the same issue.

The only way to determine what is causing the issue is to visually inspect each part individually, including battery, wire, and sensor. In most cases, only one will be causing the issue and not all of them.

You can take your car to a professional mechanic to determine what is causing the issue. It’s rare to need to replace all parts of your TPMS. So be cautious if a mechanic is recommending this.

6. ABS Issues

The ABS is your car’s braking system. Cars that have an indirect TPMS system rely on the ABS system to calculate the tire pressure. 

If your car is having issues with the ABS system this can translate to your TPMS. 

As a result, before you even know that there is an issue with your ABS system, a faulty tire pressure light can be an early indicator. 

Before you suspect this issue you should confirm that your car has an indirect TPMS. You can typically find this out by reading your owners manual or doing a simple google search. 

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