Why Is My Tire Pressure Light Still On After Filling Tires?

Embarking on a journey often brings unexpected challenges, like the persistent glow of the tire pressure light on your dashboard. In this short article, we delve into the intricacies of the Tire Pressure Monitoring System (TPMS), to find out what are the key reasons for the tire pressure light still being on after filling tires. Without further ado, let’s begin:

Incorrect Tire Pressure

Obviously, this is the first thing that comes to mind and the first thing to check. As the name suggests, Tire Pressure Monitoring System (TPMS) monitors the air pressure inside your tires and when the tire pressure in one or more of your tires falls significantly below the recommended level, or if there is a sudden drop in pressure, the TPMS light on your dashboard will illuminate. This light is an indicator of incorrect tire pressure.

Maintaining the correct tire pressure is essential for your safety, fuel efficiency, tire longevity, and overall vehicle performance. It's important to check your tire pressure regularly (at least once a month) and inflate them to the recommended pressure specified in your vehicle's owner's manual or on the driver's side door jamb. If the TPMS light comes on, it's crucial to address the issue promptly to ensure your tires are properly inflated and safe for driving.

Underinflated Tires and TPMS Light:

  • Illumination of TPMS Light: When a tire is underinflated, it doesn't have enough air to support the weight of the vehicle properly. The TPMS sensors detect this low pressure and trigger the TPMS warning light on your dashboard.
  • Causes TPMS Light to Stay On: If you've filled your tires to the correct pressure but the light persists, it's possible that one or more tires are still slightly underinflated. The TPMS has a threshold below the recommended pressure; if the pressure is close to the threshold but not quite there, the light might remain on.
  • Temperature Changes: Cold weather causes tire pressure to drop. If you filled your tires when it was warm and the temperature subsequently dropped significantly, the tire pressure could fall below the threshold, causing the TPMS light to come on.

Overinflated Tires and TPMS Light:

  • TPMS Threshold: Just like with underinflated tires, overinflated tires can also trigger the TPMS light. If you inflate your tires above the recommended pressure, it can exceed the TPMS threshold, leading to the light coming on.
  • Risks of Overinflation: Overinflated tires are more rigid and have a smaller contact patch with the road. This can lead to a harsher ride, reduced traction (especially in wet conditions), and increased risk of a blowout, especially on rough roads.

TPMS Sensor Malfunction

TPMS (Tire Pressure Monitoring System) sensors are small devices located inside the tires of your vehicle. They are responsible for monitoring the air pressure in each tire and sending this information to your car's onboard computer system. When a TPMS sensor malfunctions, it can cause various issues and affect your driving experience:

Causes of TPMS Sensor Malfunction:

  • Sensor Battery Depletion: TPMS sensors have batteries inside them that power the sensor's functions. These batteries have a limited lifespan, typically ranging from 5 to 10 years. When the battery depletes, the sensor stops working, leading to a malfunction.
  • Sensor Damage: TPMS sensors are mounted inside the tire, making them susceptible to damage from road debris, potholes, or accidents. Physical damage can disable the sensor or cause inaccurate readings.
  • Corrosion: Exposure to moisture, road salt, or other environmental factors can lead to corrosion of the TPMS sensor, affecting its performance.
  • Electronic Interference: Electronic interference from nearby sources, such as certain aftermarket devices or electronic equipment, can disrupt the communication between the TPMS sensors and your vehicle's computer system.
  • Faulty TPMS Module: Sometimes, it's not the sensors but the TPMS module in your vehicle that is malfunctioning. The module might not be receiving signals from the sensors correctly, leading to inaccurate readings or the TPMS light staying on.

Signs of TPMS Sensor Malfunction:

  • TPMS Warning Light: If a TPMS sensor malfunctions or the system detects abnormal tire pressure, the TPMS warning light on your dashboard will illuminate. If the light stays on even after checking and adjusting the tire pressure, it indicates a sensor issue.
  • Inaccurate Readings: If your TPMS displays inconsistent or inaccurate tire pressure readings, it might be a sign of a malfunctioning sensor.
  • No Signal: Some advanced TPMS systems display individual tire pressures on your dashboard. If one or more tires show no signal or a constant value, it suggests a problem with the corresponding sensor.

Repair and Replacement:

  • Diagnosis: If you suspect a TPMS sensor malfunction, a mechanic can use specialized diagnostic tools to identify the faulty sensor.
  • Replacement: Malfunctioning TPMS sensors usually need to be replaced. It's essential to replace the sensor with the exact type specified by your vehicle manufacturer.
  • Reprogramming: After sensor replacement, the new sensor may need to be programmed into your vehicle's TPMS system. This process varies by vehicle make and model.
  • Regular Maintenance: Regularly inspect your TPMS sensors during tire changes or maintenance checks. This can help identify issues early and prevent sudden sensor failures.

If you suspect a TPMS sensor malfunction, it's best to have your vehicle inspected by a professional mechanic. They can diagnose the problem accurately and ensure your TPMS system is functioning correctly, promoting both your safety and the longevity of your tires.

For more information about TMPS: A Comprehensive Guide to Tire Pressure Monitoring System (TPMS) Sensors.

Sensor Battery Depletion

TPMS sensors use batteries to power their internal components, including the sensor itself and the radio frequency transmitter. These sensors are usually mounted inside the tire, where they continuously monitor the tire pressure. Over time, the batteries inside these sensors will naturally deplete, leading to sensor malfunction. Here's more detailed information about sensor battery depletion:

1. Limited Lifespan:

  • Typical Lifespan: TPMS sensor batteries typically have a lifespan ranging from 5 to 10 years, depending on the sensor's design and the type of battery used.
  • Usage Patterns: The lifespan of the sensor battery is affected by how frequently the vehicle is driven. Sensors in vehicles that are driven more often may deplete their batteries faster.

2. Signs of Battery Depletion:

  • TPMS Warning Light: When the battery inside a TPMS sensor is depleted, it may fail to transmit tire pressure data to the vehicle's computer. As a result, the TPMS warning light on the dashboard will illuminate, indicating a problem.
  • Inaccurate Readings: Depleted batteries can lead to inaccurate or inconsistent tire pressure readings on the dashboard display.
  • No Signal: In some cases, the TPMS system might display a constant value or show "no signal" for a particular tire, indicating a sensor issue.

3. Effects of Depleted Batteries:

  • Loss of Functionality: Once the battery is fully depleted, the TPMS sensor essentially becomes non-functional. It can no longer transmit tire pressure data to the vehicle's computer system.
  • Safety Concerns: Malfunctioning TPMS sensors can compromise your safety by not providing accurate tire pressure information. Proper tire pressure is crucial for vehicle stability, handling, and braking.

4. Replacement of TPMS Sensors:

  • Entire Unit Replacement: TPMS sensors are often sealed units, and their batteries cannot be replaced separately. When the battery depletes, the entire sensor unit usually needs to be replaced.
  • Battery Life Consideration: When purchasing new TPMS sensors, it's important to consider the expected battery life. Some newer sensors come with longer-lasting batteries, which can reduce the frequency of replacements.

5. Maintenance and Replacement:

  • Regular Inspections: During routine tire maintenance or changes, it's advisable to have the TPMS sensors inspected. Mechanics can check for signs of sensor battery depletion and replace sensors as needed.
  • Sensor Types: There are different types of TPMS sensors (direct and indirect), and the replacement procedure varies. Direct TPMS sensors need to be replaced when the battery depletes, while indirect TPMS systems might not require sensor replacements as they use the vehicle's existing ABS sensors to indirectly monitor tire pressure.

Modern Car Dashboard

System Calibration

System calibration in the context of a vehicle's Tire Pressure Monitoring System (TPMS) refers to the process of resetting or recalibrating the TPMS sensors to ensure accurate tire pressure readings. This calibration is necessary in several situations:

1. Tire Rotation:

When you rotate your tires, their positions change. TPMS sensors are programmed to monitor specific tires. After rotation, the system needs to be recalibrated to recognize the new tire positions.

2. Tire Replacement:

When you replace a damaged or worn-out tire with a new one, the TPMS system should be calibrated to recognize the new sensor on the replacement tire.

3. Sensor Replacement:

If a TPMS sensor is replaced due to malfunction or battery depletion, the system must be calibrated to recognize the new sensor's unique ID and pressure data.

4. Change in Tire Pressure:

Sometimes, if you adjust the tire pressure significantly, the TPMS system might need to be recalibrated to accurately reflect the changes.

5. Reinitialization After Low Pressure or Flat Tire:

After fixing a flat tire or re-inflating a significantly underinflated tire, some TPMS systems require reinitialization to ensure proper functioning.

How Calibration Works:

  • Manual Calibration: Some vehicles have a manual calibration process that involves pressing a button or using specific controls in the car. Consult your vehicle's owner's manual for instructions on how to manually calibrate the TPMS system.
  • Automated Calibration: Many modern vehicles have automated TPMS systems that calibrate themselves as you drive. These systems detect the rotation of the tires and adjust the sensor positions automatically.

Importance of Proper Calibration:

  • Accurate Readings: Proper calibration ensures that the TPMS system provides accurate tire pressure readings. This information is crucial for your safety, fuel efficiency, tire longevity, and overall vehicle performance.
  • Early Issue Detection: Calibrated sensors can quickly detect issues such as low tire pressure or a flat tire, allowing you to address the problem before it becomes a major safety concern.

Tips for Calibration:

  • Consult Your Manual: Always refer to your vehicle's owner's manual for specific instructions on TPMS calibration procedures. Different vehicles may have different calibration methods.
  • Professional Assistance: If you're unsure about the calibration process or if you're experiencing issues with your TPMS system, it's advisable to seek professional help. Mechanics and technicians have the necessary tools and expertise to perform accurate system calibration.

Proper calibration of your TPMS sensors is essential to ensure that your system functions accurately, providing you with timely and reliable tire pressure information for a safe driving experience.

Cold Weather

Low Tire Pressure Crystal Icon

Cold weather can significantly impact your vehicle's tire pressure, which, in turn, can trigger the tire pressure monitoring system (TPMS) light on your dashboard. Here's how cold weather affects tire pressure and why it might cause the TPMS light to illuminate:

1. Tire Pressure Changes:

  • Cold Contraction: In cold temperatures, the air inside your tires contracts, leading to a decrease in tire pressure. For every 10-degree Fahrenheit drop in temperature, tire pressure can drop by 1 to 2 pounds per square inch (psi). Cold weather, especially during winter months, can cause a significant drop in tire pressure overnight or when the car is parked for an extended period.

2. Effects on TPMS Light:

  • Threshold Sensitivity: TPMS systems have a threshold below the recommended tire pressure. If the pressure in any of your tires falls below this threshold due to cold weather, the TPMS light will illuminate to indicate that there's a problem.
  • Common Cold Weather Trigger: The most common reason for the TPMS light to come on during cold weather is the decrease in tire pressure. Even if the pressure is just a few psi below the recommended level, it can trigger the TPMS warning.

3. What to Do:

  • Check Tire Pressure: If your TPMS light comes on during cold weather, the first thing to do is check the tire pressure in all your tires, including the spare. Use a reliable tire pressure gauge and inflate the tires to the recommended levels specified in your vehicle's owner's manual or on the driver's side door jamb.
  • Recheck After Warming Up: Tire pressure can increase as the tires warm up due to driving. Recheck the tire pressure after driving for a while to ensure they are within the recommended range.
  • Regular Monitoring: During the winter months, it's a good practice to check your tire pressure regularly, especially when there are drastic temperature fluctuations. Keeping the tires properly inflated not only ensures your safety but also helps with fuel efficiency and tire longevity.

4. TPMS Reset:

  • Consult the Manual: If you've checked and adjusted the tire pressure correctly, and the TPMS light is still on, refer to your vehicle's owner's manual for instructions on how to reset the TPMS system. This process varies by vehicle make and model.
  • Professional Inspection: If the TPMS light continues to stay on despite proper tire inflation and following the reset procedures, it's advisable to have your vehicle inspected by a mechanic. There might be an issue with one of the TPMS sensors or the system itself that requires professional diagnosis and repair.

TPMS Reset

Resetting the Tire Pressure Monitoring System (TPMS) is necessary in several situations, such as when you have adjusted your tire pressure, replaced a tire, rotated your tires, or when the TPMS light is illuminated on your dashboard without an apparent reason. Resetting the TPMS system helps ensure that it accurately monitors your tire pressure and provides you with timely warnings in case of underinflated or overinflated tires. Here's how you can perform a TPMS reset:

1. Manual TPMS Reset:

  • Check the Manual: First, consult your vehicle's owner's manual. It will provide specific instructions on how to reset the TPMS for your particular make and model.
  • Locate the Reset Button: Some vehicles have a reset button typically located under the steering wheel. Press and hold this button until the TPMS light blinks several times. Release the button.
  • Drive the Vehicle: After resetting, drive your vehicle for a few miles at a speed above 30 mph (48 km/h). The TPMS system should recalibrate during this time.

2. Relearn Procedure:

  • Start the Engine: Make sure your vehicle is in the "On" position or start the engine.
  • Press Reset Button: For some vehicles, you may need to press the reset button multiple times until the TPMS light blinks.
  • Wait for Initialization: Once the TPMS light blinks, wait for a few minutes for the system to initialize. The light should stop blinking and stay off if the reset is successful.

3. Use TPMS Tool:

  • Purchase a TPMS Tool: You can buy a TPMS reset tool from an auto parts store. These tools can communicate with your vehicle's TPMS system.
  • Connect the Tool: Plug the TPMS tool into your car's OBD-II port, which is usually located under the dashboard near the steering column.
  • Follow the Instructions: The TPMS tool will guide you through the reset procedure. This method is particularly useful if manual reset procedures do not work.

4. Consult a Professional:

  • Visit a Mechanic: If you're unable to reset the TPMS system using the manual or a TPMS tool, consider visiting a mechanic or your vehicle dealership. They have specialized equipment and expertise to diagnose and reset the TPMS system.
  • Software Updates: Sometimes, TPMS issues can be resolved through software updates performed by professionals.

5. Important Considerations:

  • TPMS Light Behavior: After a successful reset, the TPMS light should turn off. If it continues to stay on, there might be an underlying issue with the sensors or the system that requires professional attention.
  • Regular Maintenance: Proper tire maintenance, including regular pressure checks and adjustments, can prevent unnecessary TPMS light activations. It's crucial to keep your tires properly inflated according to the manufacturer's recommendations.

For more information: