What to Do When Your Tire Pressure Light Is Flashing

replacing a tire blowout
Just 6 PSI Tire Pressure Underinflation can Cause a Tire Blowout. https://www.gettyimages.com/license/157506266

Tire pressure is critically important for several reasons. Under-inflated tires wear out faster, force the vehicle to use more fuel, hydroplane more readily, and don’t grip the road as well. Most critically, under-inflated tires can lose traction in turns and on braking, which can make everyday driving dangerous. Finally, studies have shown under-inflation, as little as 6 psi under tire pressure specification, can lead to .

The first passenger car to adopt a tire pressure monitoring system (TPMS) was the 1986 Porsche 959, but it took a series of tire failures, as well as mounting evidence that people simply weren’t  to this critical safety component, for the National Highway Traffic Safety Administration (NHTSA) to finally mandate direct-TPMS on all passenger vehicles in the mid-2000s.

How Does TPMS Work?

tire pressure sensor valve stem cap
“TPMS Inside” Indicates a Tire Pressure Sensor, Hidden, but Critical. https://www.gettyimages.com/license/185284096

Since 2008, 100% of all vehicles on the road are equipped with direct-TPMS. Before 2008, varying numbers of vehicles were equipped with indirect-TPMS or direct-TPMS. Both systems are designed to alert drivers if one or more tire pressure readings are dangerously low.

For older vehicles, indirect-TPMS doesn’t measure tire pressure directly, but uses tire rotation speed to compare wheels and tires to each other. It can do this because tire rotation speed is directly related to tire circumference, and tire circumference is directly related to tire radius, which is directly related to tire pressure. Put simply, lower tire pressure results in a “smaller” tire, which spins faster. By comparing rotation speeds, using wheel speed sensors (WSS), the TPMS module can calculate that tire pressure is low in one or two tires.

For some older vehicles and all post-2008 vehicles, direct-TPMS is more reliable, because it takes direct pressure readings from each tire. are also available, for practically any vehicle on the road. TPMS sensors, usually part of the tire valve—some are banded to the center of the wheel—directly measure tire pressure and use radio signals to communicate this data to the TPMS module. 

What if the Tire Pressure Light Is Flashing?

Tire pressure light
If your Tire Pressure Light is Flashing, Check Your Tires. https://www.gettyimages.com/license/165655572

On some vehicles, the TPMS module communicates this information to the driver using a TPMS warning light, while others may include a direct pressure reading in the instrument cluster or information display. There are at least a couple reasons why the TPMS warning light will flash, as well as deliver other messages to the information display.

  • Low tire pressure may cause the tire pressure light to flash. If this is happening, the first thing you should do is pull over safely and inspect your tires. Use a tire pressure gauge to check that all four wheels are at specification. Use a tire inflator to bring any underinflated tires to specification or replace the tire with the spare. Bring your vehicle to a tire shop to have it repaired.
  • Faulty TPMS is another common reason for TPMS warning light flashing, but the cause may not be so obvious. On direct-TPMS systems, this may indicate a dead TPMS sensor battery, faulty TPMS sensor, or a faulty TPMS module. Check tires to be sure they are safely inflated, and head to a tire shop to have the TPMS system diagnosed.
  • Failure to Initialize is usually applicable to older indirect-TPMS vehicles, but some direct-TPMS vehicles may require “initialization” before use. Any time tire pressure is adjusted, or the wheels are removed from the vehicle, TPMS should be reinitialized to set detection thresholds. Otherwise, TPMS may falsely indicate a tire pressure problem where there is none. Check and adjust tire pressure to be sure there are no actual problems, then perform the initialization procedure, which is usually located in the owner’s manual.

Don't Ignore the TPMS Light

flat tire
Flat Tire – Just One Reason for a Flashing Tire Pressure Warning Light. https://www.gettyimages.com/license/829993790

If you have a flashing tire pressure light, it could indicate a tire pressure problem or a TPMS problem. light or your tires, as this could end up costing you in extra fuel, decreased tire life, poor traction and stability, and possible tire blow outs. It only takes a few minutes to check and adjust tire pressure and reinitialize TPMS, but if the warning light keeps flashing, the best thing to do is go to your trusted tire shop for diagnosis and repair.