How do I know if my tire pressure sensor is bad?
If your vehicle's tire pressure monitoring system (TPMS) light is illuminated on the dashboard, it could indicate a problem with one or more of your tire pressure sensors. Identifying a bad tire pressure sensor is important to ensure proper tire inflation and maintain safe driving conditions. In this article, we'll guide you through the steps to determine if your tire pressure sensor is malfunctioning.
Symptoms of a Bad Tire Pressure Sensor
The primary symptom of a bad tire pressure sensor is the illumination of the TPMS warning light on your dashboard. This light may come on for a variety of reasons, including low tire pressure, a sensor malfunction, or a problem with the TPMS system itself. Other signs of a bad tire pressure sensor include:
- Inconsistent or inaccurate tire pressure readings
- Frequent TPMS warning light activation
- Inability to reset the TPMS system after adding air to the tires
- Sensor-related error codes displayed on your vehicle's diagnostic system
If you notice any of these symptoms, it's essential to have your tire pressure sensors inspected by a qualified mechanic to determine the root cause of the issue.
Diagnosing a Bad Tire Pressure Sensor
To diagnose a bad tire pressure sensor, your mechanic will typically follow these steps:
- Perform a visual inspection of the tire pressure sensors, checking for any physical damage or corrosion.
- Use a TPMS diagnostic tool to check the sensor's signal strength and battery life.
- Verify the sensor's functionality by comparing the readings from the sensor to a known-good tire pressure gauge.
- Check for any error codes related to the TPMS system using an automotive diagnostic scanner.
If the sensor is found to be malfunctioning, your mechanic will likely recommend replacing the faulty sensor to restore proper TPMS operation and ensure accurate tire pressure monitoring.
Preventing Tire Pressure Sensor Failure
To help extend the life of your tire pressure sensors and prevent premature failure, consider the following tips:
- Regularly check and maintain proper tire inflation pressure, as recommended by your vehicle manufacturer.
- Avoid exposing the sensors to excessive heat, such as from brake components or exhaust systems.
- Ensure the sensors are properly installed and sealed to protect them from moisture and debris.
- Replace the sensors at the recommended intervals, as specified in your vehicle's maintenance schedule.
By following these best practices, you can help ensure your tire pressure sensors continue to function reliably and keep your vehicle's TPMS operating as intended.
What happens when a tire pressure sensor goes bad?
If a TPMS sensor is bad, the vehicle may have an illuminated TPMS warning light, display incorrect or fluctuating pressure readings, and the driver may experience a loss of safety features. Inaccurate or absent warnings can lead to driving with underinflated tires, which decreases fuel economy, increases tire wear, and reduces vehicle handling and braking efficiency, increasing the risk of an accident.
Symptoms of a bad TPMS sensor
- Illuminated TPMS light: The warning light on the dashboard stays on even when all tires are properly inflated.
- Inaccurate readings: The pressure displayed in the vehicle's information system does not match the actual pressure when manually checked.
- Fluctuating readings: Tire pressure values jump around erratically.
- No data displayed: A blank screen or error message may appear for one or more tires.
- Frequent alerts: The system repeatedly triggers false alarms about low or high pressure.
- Issues after service: Problems appear shortly after tire replacement or rotation.
Consequences of driving with a bad sensor
- Reduced safety: Without proper alerts, you may not know if a tire is dangerously underinflated, which can reduce traction, steering response, and braking efficiency. This increases the risk of accidents, especially in slippery conditions.
- Decreased fuel economy: Underinflated tires increase rolling resistance, forcing the engine to work harder and burn more fuel.
- Premature tire wear: Uneven wear occurs on underinflated tires, leading to a shortened lifespan and the need for earlier replacement.
What to do
- Do not ignore it: While you can technically drive with the TPMS light on, it's not recommended due to the safety and performance issues it can cause.
- Check your tire pressure manually: Even with a faulty sensor, manually check the pressure in all your tires to ensure they are properly inflated.
- Have it diagnosed and replaced: A professional can diagnose the specific sensor that is failing and replace it. The TPMS sensor batteries typically last 5-10 years and will eventually need replacement.
How to check for a bad tire pressure sensor?
You can check for a bad tire pressure sensor by looking for symptoms like a dashboard warning light despite proper tire inflation, erratic pressure readings, or a failure to get an alert when a tire is low. To pinpoint the issue, use a TPMS diagnostic tool to check each sensor, or try the manual method of deflating each tire one by one in a "relearn" mode and seeing which one fails to trigger a response from the system. A faulty sensor can also be identified with an OBD-II scanner, which can read specific fault codes and point to the bad sensor.
Method 1: Use a TPMS diagnostic tool
- Go to an auto parts store and use a TPMS scan tool or have an employee use one for you.
- The tool will activate each sensor and display its status and pressure reading.
- Compare the tool's pressure reading with a manual tire pressure gauge to ensure accuracy.
- A sensor that fails to respond or shows a significantly different reading is likely bad.
Method 2: The manual relearn method
- Ensure all tires are inflated to the recommended pressure.
- Put your vehicle in "relearn" or "programming" mode. This is often done by turning the ignition on and off a specific number of times, or as described in your car's manual.
- Release air from one tire and wait for the car to beep or chirp, which indicates it has detected the pressure change from that sensor.
- Repeat this process for each tire. The sensor that does not trigger the response is the faulty one.
- Refill the tire you deflated and then add air back to the others to the correct pressure.
Method 3: Use an OBD-II scanner
- Connect an OBD-II scanner to your vehicle's diagnostic port.
- Follow the scanner's instructions to read the TPMS data and fault codes.
- The scanner may provide a specific code, such as C1503, that indicates which sensor is malfunctioning.
- A professional mechanic can use these codes to confirm the faulty sensor.
Other symptoms to look for
- Dashboard warning light: The TPMS warning light on your dashboard stays on even after you have checked the tire pressure and it is correct.
- Inaccurate readings: The pressure display shows fluctuating or incorrect numbers for one or more tires.
- No data: The display shows no reading or an error message for a specific tire.
- Repeated false alarms: The system frequently gives false alerts about low or high pressure, even when the tire pressure is stable.
How much should it cost to replace a tire pressure sensor?
Replacing a single tire pressure sensor (TPMS) typically costs $50 to $250, depending on factors like the vehicle make and model, sensor type, and labor costs. Replacing all four sensors can be more cost-effective per sensor, with total costs potentially ranging from $400 to over $950 depending on whether you buy OEM or aftermarket parts and the labor rate of the shop.
Cost breakdown
- Parts: A single sensor can cost anywhere from $20 to over $100, with OEM sensors being more expensive than aftermarket options.
- Labor: Expect to pay between $50 and $100 in labor per sensor for installation. Some shops may offer package deals for replacing all four at once.
- Total cost for one sensor: Combining parts and labor, the cost for one sensor can range from $50 to $250.
- Total cost for all four: Replacing all four sensors could cost $400 to $950 or more, especially at a dealership.
How to save money
- Purchase parts yourself: Buy your own sensors from a parts store or online and have a tire shop install them.
- Wait for new tires: If you plan to get new tires soon, replace the TPMS sensors at the same time to combine labor costs.
- Shop around: Get quotes from different independent mechanics and tire shops, as prices can vary significantly.
Other considerations
- Aftermarket vs. OEM: Aftermarket sensors can be cheaper, but they may have compatibility issues or a shorter lifespan.
- Vehicle make and model: Luxury or newer vehicles may require more expensive or specialized sensors.
- DIY: If you have the right tools, you can replace the sensor yourself, but you'll need a special tool to activate the new sensor after installation.
How do I know if I need new TPMS sensors?
You may need new TPMS sensors if the warning light stays on after you've properly inflated your tires, if the system shows inaccurate readings, or if the light blinks and then turns solid, which indicates a system malfunction. Additionally, sensors have a lifespan of about 5 to 10 years and their batteries will eventually die, so they may need to be replaced as part of routine maintenance.
Signs of a faulty sensor
- Persistent TPMS light: The light remains on after all tires are inflated to the correct pressure, which is often found on a sticker inside the driver's side door jamb.
- Flashing light: A blinking TPMS light that then turns solid is a strong indicator that the system has a malfunction and at least one sensor is not communicating properly.
- Inaccurate or missing data: Your vehicle's display shows incorrect tire pressure, or a blank or error message for one or more tires.
- False alarms: The system repeatedly alerts you to low pressure when the tires are properly inflated.
- Issues after tire service: The warning light comes on or a sensor fails shortly after getting new tires, which could be due to damage during the installation or a sensor that was already failing.
When to consider replacement as a preventative measure
- Sensor age: TPMS sensors have a limited lifespan of about 5 to 10 years, as their internal batteries will eventually die.
- When replacing tires: It is often cost-effective to replace the sensors at the same time you are changing your tires, since the tires must be removed to access the sensors anyway.
