How To Tell If Tire Sensor Is Bad

Determining if a tire pressure sensor (TPMS) is bad can save you time, money, and potential safety hazards. A faulty TPMS sensor can lead to inaccurate tire pressure readings, triggering dashboard warnings and potentially affecting your vehicle's handling and fuel efficiency. This article provides a comprehensive guide to help you identify a bad tire sensor, understand why it matters, and explore what to do next.

How to Tell if a Tire Sensor Is Bad

Several indicators can point to a malfunctioning tire pressure sensor. Here's a breakdown of the most common signs:

1. Dashboard Warning Light Remains On

The most obvious sign of a potential TPMS issue is a tire pressure warning light on your dashboard that stays illuminated even after you've confirmed that your tire pressures are within the recommended range. This could indicate a problem with one or more of your TPMS sensors. Sometimes, the light might flash for a minute or two upon starting the car before remaining solid, signaling a more serious system fault rather than simply low pressure.

2. Inaccurate Tire Pressure Readings

If your car displays individual tire pressures, compare those readings with the pressures you measure manually using a reliable tire pressure gauge. A significant discrepancy between the TPMS reading and the manual reading suggests a faulty sensor. For instance, if your TPMS displays 25 PSI while your gauge reads 32 PSI, the sensor is likely inaccurate.

3. Sensor Doesn't Register Tire Pressure

Some TPMS systems show a "--" or "0" instead of a pressure reading for one or more tires. This usually indicates that the sensor isn't communicating with the vehicle's computer. Possible causes range from a dead battery in the sensor to a damaged sensor unit.

4. Physical Damage to the Sensor

While less common, physical damage to the sensor can occur during tire changes or road hazards. If you’ve recently had your tires changed, or hit a curb hard, it's possible the sensor was damaged. Visual inspection (though often requiring tire removal) can sometimes reveal cracks or breaks in the sensor housing.

5. Sensor Battery Depletion

TPMS sensors are battery-powered, and like all batteries, they have a limited lifespan, typically 5-10 years. A dead or weak battery is a common cause of sensor failure. Unfortunately, most TPMS sensors are sealed units, meaning the battery cannot be replaced separately from the entire sensor.

6. Corrosion

Environmental factors like road salt and moisture can corrode the sensor, especially at the valve stem. Check for visible signs of corrosion around the valve stem. Excessive corrosion can interfere with the sensor’s ability to function correctly.

7. Car Battery Issues

Although less direct, a weak car battery can sometimes trigger false TPMS warnings. Ensure your car battery is in good health, especially if you notice other electrical glitches. If the car battery dips below a certain voltage when starting, it may cause the TPMS to act erratically. This is not as common, but worth checking as well.

Why This Matters

A functioning TPMS is crucial for several reasons:

• Safety: Underinflated tires can lead to reduced handling, increased braking distance, and a higher risk of tire blowout, all of which compromise safety.
• Fuel Efficiency: Properly inflated tires optimize fuel economy. Underinflated tires increase rolling resistance, forcing your engine to work harder and consume more fuel.
• Tire Longevity: Maintaining proper tire pressure extends the life of your tires by ensuring even wear. Underinflation causes the edges of the tire to wear prematurely.
• Environmental Impact: By improving fuel efficiency, a functioning TPMS helps reduce your vehicle's carbon footprint.
• Compliance: Many countries and regions mandate TPMS systems in vehicles. A malfunctioning TPMS can lead to failing vehicle inspections.

Choosing the Right TPMS Sensor Replacement

If you've determined that a TPMS sensor is bad, you'll need to replace it. Here's what to consider when choosing a replacement sensor:

• OEM vs. Aftermarket: You can choose between Original Equipment Manufacturer (OEM) sensors or aftermarket sensors. OEM sensors are made by the vehicle manufacturer or a supplier they specify and are guaranteed to be compatible with your vehicle. Aftermarket sensors are typically less expensive but may require programming to work correctly with your vehicle's system.
• Compatibility: Ensure the replacement sensor is compatible with your vehicle's make, model, and year. Check the sensor's specifications to verify its frequency (e.g., 315 MHz, 433 MHz) matches your vehicle's TPMS.
• Sensor Type: There are two main types of TPMS sensors: direct and indirect. Direct TPMS uses sensors inside the tire to measure pressure directly, while indirect TPMS relies on the vehicle's anti-lock braking system (ABS) to estimate tire pressure based on wheel speed. Most modern vehicles use direct TPMS.
• Programming: Some aftermarket sensors require programming to be recognized by your vehicle's computer. This may involve using a special TPMS programming tool. Check if the sensor comes pre-programmed or if you'll need to have it programmed by a professional.
• Quality and Reputation: Choose sensors from reputable brands with positive reviews. Read customer reviews to gauge the sensor's reliability and performance.
• Professional Installation: While some DIYers might attempt TPMS sensor replacement, it's generally recommended to have it done by a qualified mechanic. They have the necessary tools and expertise to properly install and program the sensors.

Real-World Owner Experiences

Many vehicle owners share their experiences with faulty TPMS sensors online. A common scenario involves a TPMS warning light illuminating seemingly randomly, even when tire pressures are correct. Some owners report replacing all four sensors at once to avoid future issues, while others opt to replace only the faulty sensor. Programming difficulties with aftermarket sensors are also a recurring theme. Owners often emphasize the importance of professional installation and programming to ensure proper functionality.

Here are some summarized experiences:

• Sudden warnings on cold days: Many people experience TPMS warnings when the temperature drops significantly. This is usually due to the natural decrease in tire pressure in cold weather, not necessarily a faulty sensor, but checking the sensors functionality is still wise.
• Battery failure after 5-7 years: Most TPMS sensors last around 5-7 years, and after that, battery failure is common. Replacing all sensors at once is a popular solution to avoid repeated trips to the mechanic.
• Aftermarket sensor compatibility issues: Some aftermarket sensors don't communicate properly with the car's computer, leading to persistent warning lights even after installation. Professional installation is generally recommended to avoid these problems.
• Corrosion causing sensor failure: In areas with harsh winters and road salt, corrosion can damage the sensor's valve stem, leading to leaks and sensor malfunction.

FAQs

Q: Can I drive with a bad TPMS sensor?

A: Yes, you *can* drive with a bad TPMS sensor, but it's not recommended. While the car will still operate, you won't receive accurate tire pressure readings, which can compromise safety, fuel efficiency, and tire life. The constant warning light can also be distracting.

Q: How much does it cost to replace a TPMS sensor?

A: The cost to replace a TPMS sensor varies depending on the sensor type (OEM vs. aftermarket), vehicle make and model, and labor rates. Expect to pay anywhere from $50 to $200 per sensor, including installation.

Q: Can I replace a TPMS sensor myself?

A: While some experienced DIYers might be able to replace a TPMS sensor, it's generally recommended to have it done by a professional. Tire removal, sensor installation, and programming (if necessary) require specialized tools and expertise.

Q: Do I need to replace all four TPMS sensors at once?

A: Not necessarily, but it's often recommended to replace all four sensors at the same time, especially if they are all of similar age. This prevents future issues and saves on labor costs in the long run.

Q: Will a bad TPMS sensor affect my car's performance?

A: A bad TPMS sensor itself won't directly affect your car's engine performance. However, it can indirectly affect performance by leading to underinflated tires, which reduce handling, increase braking distance, and decrease fuel efficiency.

Q: Can a tire shop fix my TPMS?

A: Yes, most tire shops are equipped to diagnose and repair TPMS issues. They can replace faulty sensors, program new sensors, and reset the TPMS system.

Q: What should I do if the TPMS light comes on after I inflate my tires?

A: After inflating your tires, drive for a few minutes. The TPMS light should automatically turn off if the pressure is within the specified range. If the light persists, double-check the tire pressures and consult a mechanic to diagnose the issue.

By understanding the signs of a bad tire sensor and following the advice in this article, you can ensure your vehicle's TPMS is functioning correctly, promoting safety, fuel efficiency, and tire longevity.