Is your car’s tire pressure monitoring system (TPMS) light illuminated on the dashboard? That nagging warning is not only an annoyance, but also an indication that one or more of your tires may be underinflated—and that can be dangerous.
To address the concern, let’s get to know the TPMS system, then figure out how to extinguish its warning light.
What is TPMS?
Since 2008, the National Highway Traffic Safety Administration (NHTSA) has required all new vehicles sold in the United States to have TPMS—a technology that detects low tire inflation. TPMS is important because underinflated tires can lead to:
- Reduced fuel economy
- Poor handling
- Reduced braking performance
- A decrease in vehicle safety.
There are two primary types of tire pressure monitoring systems: indirect and direct.
- Indirect: This design uses the anti-lock brake system’s wheel speed sensors to detect low tire inflation. The setup works because an underinflated tire rotates more quickly than one that’s properly inflated. Each sensor in the system sends a signal to a control module. The module will turn on the TPMS warning light if it detects an underinflated (or in some cases, overinflated) tire.
- Direct: This design uses individual TPMS sensors (with built-in transponders) in each wheel. The sensors measure and broadcast tire pressure data to one or more receivers. If the pressure drops below a certain level, the receiver will turn on the TPMS warning light.
It’s important to note that TPMS technology is not a substitute for routine tire pressure checks. You should still use a gauge to check your vehicle’s tire pressure regularly.
What Does the TPMS Light Mean?
On most vehicles, the TPMS warning symbol is a depiction of a tire’s cross-section with an exclamation point in the middle. Some late-model cars may also display a message in the instrument cluster, instructing the driver to check the tire pressure.
When you first start your vehicle, the TPMS light should come on momentarily, then quickly extinguish. Here’s what it means if the light does not turn off:
Light remains on while driving: If the light stays on while driving, that means the system has detected one or more underinflated tires.
Light flashes while driving: A flashing TPMS light means there’s a problem somewhere in the system. The issue could be anything from a bad sensor to a faulty module.
Note: The TPMS warning light usually stays on when the tires are cold (usually first thing in the morning). You should see the light go out once the vehicle is driven, the tires warm up, and the pressure increases.
How to Reset the TPMS Light
As was mentioned, if the TPMS light stays on while driving (without flashing), the system has detected low pressure in one or more of the tires. Getting the light to turn off is usually pretty straightforward. On most vehicles, all you need to do is the following:
1. Determine the car’s recommended tire pressure.
You can find this information listed on a placard inside the driver’s side door jamb. Do NOT inflate the tires to the pressure listed on the sidewall—that is the maximum pressure.
2. Set the tires to the correct pressure using an air compressor, a tire chuck, and a tire pressure gauge.
If you don’t have access to these tools, you can use an air pump at a gas station or take your vehicle to a tire shop (most shops will check tire pressure for free).
Warning: If the tire pressure is substantially low, there’s a leak somewhere. Take your vehicle to a repair facility right away to have the tire fixed or replaced as needed. Underinflated tires are dangerous and can compromise vehicle safety.
3. Drive the vehicle until the light extinguishes.
If the method above does not work on your vehicle, consult your owner’s manual for the recommended process.
What is a TPMS Sensor Reset (System Relearn Procedure)?
Most vehicles require a TPMS relearn procedure when the system or the tires undergo service. For example, the procedure might be necessary when the car gets a tire rotation or a new TPMS sensor.
The steps for carrying out the relearn procedure will vary, depending on the year, make, and model of the vehicle. But generally, the process involves one of the following methods:
- Driving the vehicle for a certain amount of time at a specific speed to perform an automatic relearn.
- Putting the vehicle into a relearn mode (usually through the instrument panel), then driving at a specific speed for a certain amount of time.
- Using a scan tool to perform a relearn.
- Following the steps in the owner’s manual or service information to put the vehicle into a relearn mode. Then, triggering each sensor by adjusting the tire pressure or using a scan tool (or an activation tool).
Usually, you can find information regarding the relearn procedure in your owner’s manual. Online repair databases also have detailed relearn information from the vehicle manufacturer.
For example, here is the relearn procedure for a 2010 Chevy Silverado 1500:
- Put the vehicle in park, turn the engine off, and set the parking brake.
- Turn the ignition key to the ON position (but leave the engine off).
- Press the key fob’s lock and unlock buttons at the same time for five seconds. The horn will sound twice, and a message will display on the dash that says “Tire Learning Active.” This indicates that the vehicle is in relearn mode.
- Press the key fob’s lock and unlock buttons at the same time for five seconds. The horn will sound twice and a message will display on the dash that says “Tire Learning Active.” This indicates that the vehicle is in relearn mode.
- Remove the valve cap on the left front tire. Increase or decrease the tire’s pressure until a horn chirp sounds to confirm the sensor has been matched to the tire position.
- Move to the right front tire and repeat step five.
- Move to the right rear tire and repeat step five.
- Move to the left rear tire and repeat step five. The horn will chirp twice to confirm the sensor has been matched to the tire and wheel and that the relearn mode is no longer in progress.
- Turn the ignition switch off.
- Set all four tires to the recommended pressure listed on the placard inside the driver’s side door jamb.
How to Diagnose a TPMS Light Flashing
A flashing TPMS light indicates there’s a problem somewhere in the system. Because troubleshooting a TPMS problem often requires dedicated equipment, you might want to leave the job to a professional.
Most repair facilities will diagnose a TPMS issue by doing one or more of the following:
- Checking for diagnostic trouble codes (DTCs) related to the TPMS system. An OEM-level scan tool (not a cheap code reader) is required to check for TPMS DTCs.
- Using a handheld tester to activate each of the TPMS sensors to verify they work (this method only works on direct TPMS systems).
How Much Does TPMS Sensor Replacement Cost?
If you need to have one of your TPMS sensors replaced, expect to pay between $200 and $800 for a professional to do the job.