The low tire pressure light on your car (also known as the TPMS light) should turn off when you have filled your tires to the proper pressure in terms of PSI (pounds per square inch), so what do you do when the tire pressure light won’t go off?
Sometimes, inflating your tires to the correct pressures just doesn’t work. So why is my TPMS light on, but my tires are fine?
The light doesn’t always reset, and that can leave you with an annoying orange light or, with some newer vehicles, a constant message on your display that your tire pressure is low.
If you have ensured that the tire pressure is fine in each of your tires, including your spare (yes, they often have sensors, too), and the warning light still refuses to turn off, here are a few methods we can suggest for how to fix the TPMS warning light.
9 Reasons Your Tire Pressure Light Is on, but Tires Are Fine
The TPMS (Tire Pressure Monitoring System) doesn’t measure pressure directly in all cases; it relies on sensors, wheel speed data, or temperature compensation. When any part of that chain fails, you get a false alert.
Reason 1: Temperature Drop Overnight
TPMS sensors are calibrated at a specific temperature, usually around 68°F. When the weather cools 20°F overnight, tire pressure drops 1 PSI for every 10°F. A 30°F drop can trigger the light even if the tires were perfect the day before.
A Honda Accord owner called me in a panic last fall—the light came on after the first cold night. All tires read 32 PSI (down from 35). I explained the temperature rule, had them drive 10 miles to warm the tires, and the light reset itself. No cost, just education.
Reason 2: Faulty TPMS Sensor Battery
Most direct TPMS sensors have a 5-10-year battery. When it dies, the sensor stops transmitting. The car sees “no signal” and turns on the light, even if the pressure is perfect.
This is the #1 cause in vehicles over 7 years old. A Toyota RAV4 came in with one dead sensor. Replaced it during a tire rotation, $85 total. Light off, customer happy.
Reason 3: Damaged or Corroded TPMS Sensor
Road salt, curb hits, or tire shop errors can crack the sensor stem or corrode the valve. It fails to send data, so the system assumes low pressure.
Reason 4: Aftermarket Wheels Without Sensors
Some aftermarket wheels don’t have TPMS sensors, or the old ones weren’t transferred. The car expects four signals but gets zero. Light stays on permanently.
Reason 5: Spare Tire TPMS Sensor (Some Models)
Certain vehicles, like Jeep Wranglers and some Ford trucks, monitor the spare tire too. If the spare’s sensor fails or pressure drops below 25 PSI, the dash light activates, even if the driving tires are fine.
A Jeep owner spent two days checking door pressures before I found the spare at 18 PSI under the rear. Inflated it to 35 PSI, light gone in 30 seconds.
Reason 6: TPMS Relearn Not Performed After Tire Rotation
After rotating tires, the car needs to relearn which sensor is on which wheel. If the relearn isn’t done (or fails), the system gets confused and triggers the light.
This happens often at discount tire shops. A Chevy Equinox came in after a rotation—the light flashed for 10 minutes, then stayed solid. I used a TPMS tool to relearn in 3 minutes. $40 service.
Reason 7: Low Battery Voltage Affecting TPMS Module
The TPMS control module needs 12.6 volts to function. A weak car battery (below 12V) causes a communication error. The light comes on randomly, especially in cold weather.
Reason 8: Radio Frequency Interference (Rare)
Nearby cell towers, LED headlights, or aftermarket radar detectors can jam TPMS signals (433 MHz). The car loses sensor data and lights up the warning.
Reason 9: Software Glitch in TPMS Control Module
Like any computer, the TPMS module can glitch or be corrupted. A reset or software update from the dealer fixes it.
Why Does the TPMS Light Illuminate?
- Low tyre Pressure: The most common reason for the TPMS light to illuminate is low tyre pressure. When one or more tyres fall below the recommended pressure level, the TPMS sensor triggers the warning light to alert the driver. Proper tyre inflation is critical for optimal handling, braking, and overall vehicle safety.
- Fluctuations in Temperature: Changes in ambient temperature can impact tyre pressure. As temperatures drop, tyre pressure tends to decrease, and vice versa. If the TPMS light comes on during temperature fluctuations, it may indicate that the tyres need adjustment to accommodate the changing weather conditions.
- Faulty TPMS Sensor: In some cases, a malfunctioning TPMS sensor can trigger the warning light. Sensors can degrade over time or become damaged, leading to inaccurate pressure readings. Regular maintenance checks should include inspecting the TPMS system to ensure proper functionality.
- Tyre Puncture or Damage: A punctured or damaged tyre can cause a sudden drop in pressure, triggering the TPMS light. Inspecting the affected tyre and addressing any punctures promptly is crucial to prevent further damage and maintain safe driving conditions.
What to Do When the TPMS Light Illuminates?
- Check tyre Pressure Immediately: When the TPMS light illuminates, the first and immediate action should be to check the tyre pressure of all four tyres, including the spare. Consult your vehicle’s manual or the driver’s side door jamb for the recommended tyre pressure values. Use a reliable tyre pressure gauge to measure the pressure in each tyre.
- Add Air as Needed: If any tyre is found to have low pressure, add air to bring it to the recommended level. Most gas stations provide air pumps, and many are equipped with tyre pressure gauges for added convenience. Ensure that all tyres match the recommended pressure for your specific vehicle.
- Inspect tyres for Damage: While checking tyre pressure, visually inspect each tyre for signs of damage, such as cuts, bulges, or punctures. If you discover any visible issues, it is advisable to have the tyre inspected by a professional to determine if repairs or replacement are necessary.
- Verify Spare tyre Pressure: Don’t forget to check the spare tyre’s pressure, as it can be easily overlooked. A fully inflated spare ensures that you have a reliable backup in case of a flat tyre on the road.
- Consider Seasonal Adjustments: If the TPMS light illuminates during temperature changes, consider adjusting the tyre pressure to accommodate the seasonal variations. Consult your vehicle’s manual or a professional mechanic for guidance on the appropriate adjustments for different weather conditions.
- Visit a Professional Service Center: If the TPMS light persists or if you are unable to identify and address the issue on your own, it is advisable to visit a professional service center. Experienced technicians can conduct a thorough inspection, diagnose any underlying problems with the TPMS system or tyres, and provide necessary repairs.
- Address Faulty TPMS Sensors: If the TPMS light continues to illuminate despite proper tyre pressure, it may indicate a faulty sensor. In such cases, it is essential to have the TPMS system inspected by professionals who can identify and replace malfunctioning sensors.
Understanding Direct vs. Indirect TPMS
1. Direct.
The direct TPMS is used in most cars on the road today. With this design, all four wheels have a sensor that feeds information back to the computer. If the tire pressure gets low, a signal is sent and the alert comes on the dashboard.
Because of where the sensors are located, there can be damage to them when driving on harsh road conditions, such as dirt driveways or during service. They also go bad simply because of old age, requiring replacement over time.
2. Indirect.
Some manufacturers prefer the indirect system, which doesn’t use a sensor on each wheel. Instead, the TPMS runs from the sensors on the anti-lock brakes. These sensors determine when the rotation speed is slow, indicating that tire pressure might be low.
The indirect TPMS is considered more durable than the normal system because it doesn’t fail as often. However, you aren’t going to know if multiple tires are running low since there aren’t separate sensors.
Up until now, it’s only been some Asian and European automakers that have chosen this TPMS configuration. However, other automakers are discussing switching over, making it more of a standard option across the board.
How to Fix TPMS Light?
#1. Inflate the Tire.
The first solution is to inflate the low tire properly. The light will come on, and you should always check the tire pressures first.
You can compare the reading with the recommended air pressure on the driver’s side door jamb. If the light stays on, and the pressures are correct, you will have to go to our other tips.
#2. Repair the Fault.
The repair that you carry out will depend on what fault is being caused. If you do not have the tools to figure out what is wrong, you should take the car to a professional.
A simple TPMS sensor can cost $75 to $250 to replace, which includes the sensor and labor. A dead battery usually means that a new sensor is also needed. If the receiver is required to be changed, the cost will be slightly higher.
If you have the tools and knowledge to change the sensor and receiver, you can repair this yourself and charge only for the parts and not for the labor.
#3. Reset the Light.
If the light has come on because there was a fault after rotating the tires or servicing, you may need to reset the light. Most car makers have an easy way to reset the warning light. You will find the details in the owner’s manual.
There may be a reset button in the glove box or in the car system menu settings. Additionally, you need to know how long to hold the button and what exact steps to take to reset the light.
Can I Drive with the TPMS Light On?
You should react to a TPMS light warning if it appears on the dashboard. Your first consideration should be to pull over quick to check proper air pressure in the tires. If the tire is not inflated correctly, they could fail.
When tire is under inflating the tire could overheat and burst creating an unsafe situation. If you are not aware that the tire pressure is continuously losing air you lose control. At a minimum the tire is uneven wear, causing a friction, and the need for a new tire or tires sooner.
When the Tire Pressure Monitoring System lights up and all the tires are perfectly inflated you still would never know if there was a problem. Things such as a bad sensor ignoring it until it was too late, and instead of having tires inflated 32 psi, one could be 25 psi, creating a greater risk until it gets lower and possibly resulting a accident.
As the tires get lower, you start to deal with:
- Delayed driving response
- Additional wear to the tires
- Overheating tires
- Reduced traction
- Bumpier ride
- Less on-road control
The cost of getting the air or fixing the problem isn’t even close to the risk. You will pay a fraction for the repair compared to what liability you may face in the event of a significant crash.
Plus, a bad crash could turn someone’s life around if there are injuries. Is this really worth ignoring the helpful TPMS light?