TPMS Sensors

Proper tire pressure is critical for good handling and fuel economy, optimal tire life, and most importantly, driving safety. All passenger vehicles made since 2007 have been required to have an on-board Tire Pressure Monitoring System (TPMS) to alert the driver if the air pressure in any tire drops below 25% of the recommended cold inflation pressure. Like any electronic automotive system, TPMS effectiveness depends on the system’s computer receiving accurate data, and in a direct monitoring TPMS, that requires quality TPMS sensors like the kind you’ll find on our digital shelves.

Only direct monitoring systems have TPMS sensors. The indirect monitoring systems found on some vehicles rely on the wheel speed sensors in the anti-lock braking system. The circumference of a tire, and the revolutions per mile it rotates, is reduced on an underinflated tire. The signal from that tire’s wheel speed sensor is compared by the computer to the rotational speed of the other tires and interpreted as a low tire, illuminating the TPMS warning light. However, an indirect system cannot indicate which tire is low or if all tires are uniformly low, nor can it display actual tire pressure.

Most TPMS sensors are a combination valve stem, pressure sensor and wireless transmitter, and some can even detect and transmit tire temperature. They mount to the rim in the same position as ordinary valve stems, and when viewed from the outside of the wheel, appear and function the same as well, allowing air to be added or removed from the tire. The sensor and the battery that powers it are on the inside of the wheel. These sensors can be one-piece or the valve stem can be bolted to the sensor, and the valve stem can be aluminum or rubber. A less common type of TPMS sensor is the banded sensor. Banded sensors are separate from the valve stem, installed in a cradle that is attached to the inside of the rim with a worm gear screw clamp that surrounds the circumference of the wheel.

TPMS sensors do their job in a harsh environment, exposed to the elements, dirt, road salt, road shock and vibration, and temperature extremes, all of which can cause deterioration and eventual failure. They can become damaged if mishandled during tire dismounting/mounting, and they can fail due to corrosion, particularly those with aluminum valve stems, but the most common cause of failure is a dead battery. The lifespan of original equipment TPMS sensor batteries is typically 5 to 7 years. The battery cannot be serviced separately, so if the battery is dead the entire sensor must be replaced. The same warning light that glows when a tire is low should remain on, even after the tire has been properly inflated, or flash, if there is a problem in the TPMS system, including a faulty sensor.

The most important thing you need to know if you have failed TPMS sensors is that you don’t have to go back to the dealer and pay the high dealer price for replacements. Regardless of what you drive, our sensors will directly replace and function just like the OE units, for less cash. They’ll program to your vehicle using the exact same procedure used for the factory sensors, and you can use the same scan tool if one is required. And if programming of the OE sensors can be accomplished without tools, you’ll be able to do the same with our sensors. We also have replacement valve stems for those that can be removed from the sensor, as well as service kits for sensors with integral valve stems that include the valve core, nut, seal, and cap.

But if you’re looking for a simple system that will instantly let you know a tire is underinflated, check out our LED tire watch caps. These caps mount to the valve stems in place of regular valve stem caps, and locking nuts are included to prevent theft. Just set each tire to the proper cold inflation pressure and install the LED tire watch caps. The cap self-calibrates to the tire’s inflation pressure upon installation. If tire pressure drops 5-10 psi below your set inflation pressure, the LED will flash red so brightly it can even be seen in daylight.