A tire pressure monitoring system (TPMS) is an important safety feature in modern vehicles.
It monitors the air pressure inside your tires and alerts the driver if a tire becomes significantly underinflated.
Low tire pressure can negatively impact vehicle handling, braking, and fuel economy. It also increases the risk of tire damage or failure.
The TPMS uses sensors mounted inside each wheel that transmit wireless signals to a receiver module.
The sensors monitor air pressure and transmit pressure readings.
If pressure drops 25% or more below the correct level, the TPMS triggers a warning light on your dashboard to alert you that a tire is low. This allows you to address the issue promptly.
Properly functioning TPMS sensors are critical for safety.
If the system is not reading one or more tires, it indicates a malfunction needs to be diagnosed and fixed so you can rely on the TPMS to alert you of any dangerously underinflated tires.
In this article, we’ll explore the common causes of a non-reading TPMS sensor and the steps to restore proper operation.
Possible Causes – TPMS Not Reading One Tire
There are a few common reasons why the TPMS might not be reading the pressure of one tire:
Low Tire Pressure
The most likely cause is that the tire pressure is low on that one tire.
TPMS sensors are designed to detect when the tire pressure drops 25% or more below the recommended pressure.
If the other tires are properly inflated but one is low, it may not trigger the sensor.
Always start by checking the pressure in that tire with a tire gauge.
Faulty Sensor
It’s possible the TPMS sensor attached to the wheel on that tire has malfunctioned. Sensors have a finite battery life of about 5-10 years.
Over time, the battery can die, causing the sensor to stop transmitting pressure data. Replacing the faulty sensor will resolve this.
Interference
In rare cases, certain devices like cell phone chargers can emit radio frequencies that interfere with TPMS sensors if used in close proximity.
This interference prevents signal transmission. Check for any devices plugged into the 12v outlet near the problematic tire.
Unplugging them may help determine if interference is the culprit.
Possible Causes
The TPMS module that receives data from the sensors and triggers warning lights can also malfunction.
If all the sensors are working properly but one tire still doesn’t read, the module may need to be replaced.
This is an uncommon issue but can occur. A mechanic can diagnose a faulty module.
Checking Tire Pressure
If one tire is not reading properly on the TPMS system, the first step is to manually check the pressure in that tire using an accurate tire pressure gauge.
Here are the steps:
- Remove the valve cap from the problem tire.
- Firmly press the tire gauge onto the valve stem and measure the pressure. Compare the readings to the manufacturer’s recommended tire pressure listed on a sticker inside the driver’s door jamb or in the owner’s manual.
- If the tire pressure is low, inflate the tire to the proper pressure.
- Also inspect the tire tread and sidewalls for any damage, cuts, bulges or nail punctures that could cause a slow leak and loss of pressure over time.
- If damage is found, the tire may need to be patched or replaced. Driving on an underinflated or damaged tire can lead to blowouts, uneven wear, reduced fuel economy and other safety issues.
- Be sure to check the pressure on the other tires as well. Uneven tire pressures can cause steering and handling problems.
- Securely replace the valve cap when finished.
This manual pressure check can determine if improper inflation is causing the TPMS issue, or if the problem lies with the sensor itself. Maintaining correct tire pressures is critical for safety and extends tire life.
Inspecting the Sensor
The TPMS sensor is located on the inside of each wheel, often visible behind the rim.
Locate the sensor and inspect it closely for any signs of damage or corrosion. The sensor contains a battery inside and is mounted to the wheel rim.
Look for the following issues:
- Corrosion on the sensor body or wires – This can prevent the sensor from transmitting properly. Salt, dirt and moisture are common causes of corrosion.
- Cracks or damage to the sensor body – Cracks or holes can allow water inside the sensor, damaging the electronics. Inspect the epoxy resin that seals the sensor as well.
- Broken or damaged sensor wires – The wires connecting the sensor can become frayed or severed if routed improperly. Inspect where the wires exit the sensor body.
- Low battery error – Some TPMS systems will indicate if a sensor has a low battery. Replacing the battery may resolve the issue.
- Missing mounting clip – The sensor clicks into a special mounting clip attached to the wheel. If it’s missing or broken, the sensor will not be held securely.
Carefully inspecting the TPMS sensor on each wheel will reveal any external damage that could be preventing it from reading properly. If the sensors appear undamaged, the issue likely lies with the TPMS module instead.
Interference Diagnosis
Interference from other devices can sometimes cause a TPMS sensor to stop communicating properly.
This often happens if the TPMS sensor batteries are running low, making the sensors more prone to interference.
Potential sources of interference include:
- Aftermarket electronics like remote starters, alarm systems, and audio equipment
- Charging stations and cell phone towers
- Power lines and utility equipment
- Other vehicles parked closely for extended periods
If you suspect interference is the culprit, try driving the vehicle away from any potential sources of interference like the examples above.
It’s best to have the dealership diagnose interference issues so they can pinpoint the source and recommend solutions.
Their specialized diagnostic tools can read individual sensor signals and frequencies to check for conflicts.
This allows them to identify if a new sensor is needed versus troubleshooting the interference source.
Dealerships also have access to updated software and firmware for the TPMS module, which can improve resistance to interference.
Getting the latest updates installed regularly as part of routine maintenance is a good preventative measure.
Module Replacement
If none of the previous troubleshooting steps have resolved the issue, the problem may be with the TPMS module itself.
The TPMS module receives signals from the sensors and determines if there is an issue with tire pressure.
To replace the TPMS module:
- Locate the TPMS module, usually under the dashboard or in the glove compartment. Consult your owner’s manual for the exact location.
- Have the module inspected and tested by an automotive technician, either at a dealership or local auto shop. They will be able to diagnose if the module is faulty and needs replacement.
- If the module does need to be replaced, it’s best to have the dealership or a specialized shop perform the replacement. The module will need to be reprogrammed with your vehicle’s specific TPMS settings.
- Older model vehicles may require the replacement module to be “flashed” to sync with the sensors. Newer vehicles can sometimes perform an automatic relearn procedure.
- Ensure all sensor IDs are correctly detected after module replacement and the system can read pressures from all tires. Test drive the vehicle to verify proper operation.
Replacing the TPMS module can be expensive, often $200-$300 for parts and labor.
While not an easy DIY job, module replacement is usually straightforward for an experienced technician to perform.
If you are experiencing ongoing issues with the TPMS system reading one tire, a faulty module could certainly be the culprit.
Sensor Replacement
If the TPMS sensor itself is faulty, you’ll need to replace it.
The best course of action is to purchase a new OEM sensor and have a shop install it. Here are some key steps:
Purchase the new OEM sensor – Avoid cheap aftermarket sensors, as OEM sensors have the best compatibility and reliability. Check your owner’s manual for the correct part number.
Have a shop install the new sensor – TPMS sensors require specialized tools and programming to install properly. The sensor needs to be matched to the vehicle so the tire pressure monitoring system recognizes it. A professional shop will have the necessary equipment.
Have the shop reprogram the TPMS system – After installing the new sensor, the shop will need to reset the TPMS computer and program the new sensor ID code so the system recognizes it. Each sensor has a unique serial number that must be matched on the vehicle computer.
Replacing a faulty TPMS sensor and having it properly installed and programmed is key to getting the system functioning correctly again.
Trust the job to experienced tire shop professionals, and avoid DIY installation attempts.
Investing in an OEM sensor and professional installation will pay off in the long run with seamless operation.
Resetting the System
If the TPMS system has been recently serviced or new tire sensors have been installed, a reset procedure may need to be performed so the TPMS module recognizes the new sensors.
The reset procedure is typically outlined in the owner’s manual.
The basic process involves:
- Turning the ignition on and then back off.
- Firmly press and release the TPMS reset button. On many models, the button is located under the steering wheel or on the dash.
- The horn may sound and dashboard TPMS light may flash to indicate the reset procedure has been initiated.
- Drive the vehicle for around 15 minutes above 15 mph to allow the TPMS module to detect signals from each wheel sensor.
- The TPMS light should turn off once the reset is complete and the system is reading all sensors.
If the light stays on, the sensors may need to be rescanned so the module can properly identify each one.
This involves a TPMS scan tool that sends signals to the sensors so they transmit back to the module.
A mechanic shop can perform this rescanning if the DIY reset procedure does not work.
Proper resetting and rescanning is crucial for the system to function correctly after new sensors are installed.
Refer to the factory service manual for the exact reset procedure for your vehicle.
Preventative Maintenance
Proper tire maintenance can help avoid TPMS issues and keep you safely on the road. Here are some tips:
Check tire pressure regularly – Low tire pressure can cause the TPMS to malfunction. Use a tire gauge to check each tire’s pressure monthly and inflate them to the recommended PSI level listed in your owner’s manual or on the tire placard. This helps ensure proper tire health and TPMS function.
Inspect sensors periodically – Look at the tire sensors whenever you change a tire or rotate them. Check for damage, low batteries, and proper fit. Replace any faulty or dead sensors right away. Periodically testing sensors by a professional can also identify potential problems before they occur.
Proactive tire and TPMS maintenance provides peace of mind that your monitoring system is working properly. It also reduces the chances of a flat tire or blowout, keeping you and your passengers safe. Taking the time for routine checks helps avoid the headaches of a TPMS malfunction.
When to Seek Help
If the TPMS light stays on after you’ve checked the tire pressures and inspected the sensors, there are likely deeper issues that will require professional help to resolve.
Here are some instances when you should seek assistance from a professional mechanic:
– If no tires are significantly under-inflated but the TPMS light persists, there may be a faulty sensor that needs replacement. TPMS sensors have batteries that eventually wear out and will need professional installation when replaced.
– If a new TPMS sensor has been installed but the light is still on, the sensor may not be communicating properly with the vehicle’s computer module. The module may need to be reset or replaced to function with the new sensor.
– If no sensors are damaged but the TPMS light flashes or displays error codes, the vehicle’s central computer module may be malfunctioning. This requires diagnosis and replacement by a professional mechanic.
– If there is physical damage to a tire sensor such as cracks or stripped/crossed threads, the sensor unit will need professional installation to replace.
– If there is interference from other devices causing the TPMS system to malfunction, a mechanic can determine the source and recommend solutions.
In any of these situations where the TPMS system requires deeper repairs, seek assistance from a trusted professional mechanic.
They have the knowledge and equipment to accurately diagnose TPMS issues and perform the necessary repairs to get your system functioning properly again.
Don’t continue driving with a malfunctioning TPMS light, as it indicates your tires are not being monitored for critical safety purposes.
