How do you know if your TPMS sensor is bad?

A bad TPMS (tire pressure monitoring system) sensor typically shows up as a dashboard warning light or fault message, often paired with misleading or missing tire-pressure readings. If you notice persistent warnings even after inflating tires to the recommended pressure, a closer check is warranted.

Common signs a TPMS sensor may be failing

The most frequent indicators are listed below. They can help you decide whether you should test the system or replace a sensor.

• The TPMS warning light stays on or a “TPMS Malfunction” message appears, even after inflating tires to the recommended cold pressures.


• Pressure readings from the TPMS are inconsistent between tires or don’t match readings from a handheld gauge.


• You repeatedly get a low-tire warning when tires aren’t actually underinflated.


• After tire rotation or replacement, the system won’t relearn the new positions or pressures.


• A sensor battery is suspected to be weak, sometimes accompanied by a “TPMS battery low” or similar message on the vehicle’s display.


• Visible damage to a wheel sensor, valve stem, or corrosion around the sensor area.


• The spare tire (if it carries a TPMS sensor) or a missing sensor triggers a fault in the system.

If several of these conditions show up, the fault may lie with one wheel’s sensor or with the system’s ability to read signals, rather than with routine tire pressure itself.

How to diagnose a suspected bad TPMS sensor

Use these steps to determine whether the issue is a faulty sensor, a calibration problem, or something else affecting the system.

1. Check all four tires with a reliable tire gauge to verify they’re inflated to the vehicle’s recommended cold pressures.


2. Inspect tires and wheels for punctures, slow leaks, or damage that could falsely trigger warnings.


3. Use a TPMS scan tool or visit a shop to pull fault codes and read each sensor’s status (ID, battery level, signal strength).


4. Confirm whether your vehicle uses direct TPMS (wheel-mounted sensors) or indirect TPMS (ABS-based system that infers pressure from wheel speed).


5. For direct TPMS: check each sensor’s battery condition and physical integrity; replace a failing sensor as needed and have it programmed to the vehicle.


6. For indirect TPMS: understand that it relies on ABS data and may require calibration after tire changes or rotations; it won’t display exact psi values in the same way as direct TPMS.


7. After sensor replacement or calibration, perform a relearn/initialization sequence as required by the vehicle to re-sync the sensors with the ECU.

Following these steps will typically reveal whether a sensor is defective, needs recalibration, or if the problem lies elsewhere in the tire-pressure monitoring chain.

What to do if you confirm a bad TPMS sensor

Once you identify a faulty sensor, here are the practical steps to restore proper TPMS function and safety on the road.

• Replace the defective direct TPMS sensor with a new one that matches your vehicle’s specifications, preferably OEM or a quality aftermarket unit.


• Have the new sensor programmed or relearned to your vehicle’s ECU as required; some cars need a hand-held tool or dealer/software to complete this step.


• Inspect and, if necessary, replace the valve stem hardware and check for corrosion on the wheel where the sensor resides.


• Inflate all tires to the recommended cold pressures and perform a system relearn if your vehicle requires it.


• Test drive the vehicle and monitor the TPMS indicators to confirm stability of readings across all four wheels.

Cost and timing vary by vehicle, sensor type, and the need for programming; a professional shop can usually perform diagnosis, sensor replacement, and relearn in a single visit.

Direct vs indirect TPMS: what you should know

Understanding the two main TPMS approaches helps explain warning behavior and service options.

• Direct TPMS uses battery-powered sensors embedded in each wheel to measure and transmit actual tire pressures to the car’s computer. Battery life commonly spans several years, often 5–10 or more depending on usage and environment.


• Indirect TPMS does not use wheel-mounted pressure sensors. Instead, it infers low pressure by comparing tire circumferences via ABS wheel-speed sensors, which means it cannot report exact psi values.


• Direct systems typically display real-time pressure values on the dashboard and require sensor relearns after tire changes or rotations. Indirect systems rely on software calibration and can sometimes show a general warning without exact pressures.


• Common failure points differ: direct TPMS is prone to battery failure, sensor damage, and valve-stem corrosion; indirect TPMS can misread after significant tire changes or wheel swaps and may need recalibration.


• When to replace or service: direct sensors are replaced as individual units; indirect systems may be recalibrated or checked for ABS sensor issues rather than sensor replacements.

Ask a shop which TPMS type your vehicle uses and whether sensor replacement, battery service, or software relearning is required for a reliable fix.

Summary

TPMS sensors are designed to prevent underinflated tires, a key safety factor for handling and fuel efficiency. A bad sensor usually presents as a persistent warning light, inconsistent pressure readings, or a fault message, sometimes with a weak or dead battery in the wheel sensor. Diagnosing the problem involves validating tire pressures, scanning for fault codes, and identifying whether the system is direct or indirect. Replacing faulty sensors and performing the required relearn are typically necessary to restore accurate monitoring. If you encounter a TPMS warning, treat it as an indicator that at least one tire may be outside its optimal pressure range and have the system checked promptly.

Do I need to replace all 4 TPMS sensors?

You do not have to replace all four TPMS sensors, but it is highly recommended, especially if the failure is due to a dead battery. The other sensors are the same age and will likely fail soon, so replacing them all at once is more efficient and can save you money and time on future appointments. 
Reasons to replace all four

• Batteries are short-lived: TPMS sensor batteries typically last 5 to 10 years and are not user-replaceable. If one has failed, the others are likely close to failing as well. 
• Cost-efficiency: It is more efficient to replace all four at once. You will save money on labor costs by having the tire removed only once for all sensors, rather than paying for labor four separate times. 
• Convenience: It prevents multiple future appointments, as each sensor will need to be replaced as its battery dies. 
• Timing: If you are replacing your tires anyway, now is the perfect time to replace the TPMS sensors, as the tire is already off the wheel. 

When you might replace only one

• If the sensor failed for a different reason: If a sensor fails due to physical damage (like hitting a curb) instead of a dead battery, the other sensors might still be good. 
• If you are on a tight budget: You can technically replace just the one that failed and wait to replace the others as they fail, but this is not the most efficient long-term solution. 

This video explains why you should consider replacing all four TPMS sensors at once: 53sAUMOVIO Aftermarket NAYouTube · Oct 18, 2022

What happens when a TPMS 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. 

Can AutoZone fix TPMS sensors?

At AutoZone, we carry replacement TPMS sensors for most makes and models. And if you need help resetting the TPMS light, we can offer helpful advice or refer you to a shop in our professional network.

Why is my TPMS on but my tires are fine?

If your tire pressure light is on but your tires are fine, it's likely due to a malfunctioning TPMS sensor, a need to recalibrate the system after a tire rotation, or an overinflated tire. You should first confirm the tire pressure with a reliable gauge and recalibrate the system if the pressure is correct, as described in your owner's manual. If the problem persists, have a professional inspect the TPMS sensors, as they can fail due to age, damage, or a dead battery.
 
Potential causes and solutions 
This video explains four common reasons why the tire pressure light may be on even when the tires seem fine: 46sMaxTheCarGuyYouTube · Mar 6, 2023
1. Incorrect tire pressure

• Problem: Even if tires look fine, they may be overinflated or slightly underinflated. 
• Solution: Use a high-quality tire pressure gauge to check the pressure in all four tires, including the spare if it has a sensor. Inflate them to the recommended PSI found on the sticker in your driver's side door jamb. 

2. TPMS system malfunction

• Problem: The system may be giving a false reading due to a faulty sensor, a dead sensor battery, or a general electronic issue. 
• Solution: After checking the pressure, try to reset the system. This often involves a specific sequence of turning the ignition on and off or pressing a button on the dashboard. If that doesn't work, a professional needs to diagnose and replace the faulty sensor. 

3. Recent tire service

• Problem: A recent tire rotation or replacement can trigger the light because the sensors may have been inadvertently damaged or need to relearn the new wheel positions. 
• Solution: After confirming the correct pressure, drive your car for about 10-20 minutes at a consistent speed. This may allow the system to automatically recalibrate itself. If not, a mechanic may need to perform an external recalibration. 

4. Overinflated tires

• Problem: The light can also come on if the tires are significantly overinflated, not just underinflated. 
• Solution: Check the pressure and let some air out until the tires reach the recommended PSI. 

This video shows how to reset the tire pressure light on vehicles with a display audio system: 1mHondaYouTube · May 15, 2019
Important safety note

• Do not ignore the light: Even if your tires look fine, low pressure can still cause hidden damage over time, and a malfunctioning sensor still means you won't get an accurate reading if a real problem occurs. It's crucial to get the system checked to ensure your tires are safe and properly inflated.