The purpose of the tire pressure monitoring system (TPMS) in your vehicle is to warn you that at least one or more tires are significantly under-inflated, possibly creating unsafe driving conditions. The TPMS low tire pressure indicator is a yellow symbol that illuminates on the dashboard instrument panel in the shape of a tire cross-section (that resembles a horseshoe) with an exclamation point.
TPMS involves a valve and a sensor, and it’s also important to know that not all TPMS systems are created equal. There are two kinds of TPMS technology–indirect and direct. Indirect TPMS approximates tire pressure indirectly by using data from the vehicle’s antilock brake system (ABS). Direct TPMS provides a more accurate calculation of your tire pressure using data gathered directly from a sensor placed inside each tire.
Ensuring that your TPMS valve stems have the proper cap is key to the long term life of your TPMS sensors. In our area, rock salt, and ice melting solutions, are a given. If your TPMS valve stems are missing caps the rock salt can get caught in the stem and start to break down the metal, making it hard for you to adjust the pressure in your tires.
Do not ever put metal valve caps on your TPMS valve stems. Metal caps can easily cause corrosion on the threads of TPMS stems as well as beginning to corrode themselves. The result is all too often that the cap will rust-weld itself to the stem, leading to outcomes from the cap simply seizing when a technician tries to remove it, to cross threading issues, or even having the stem break off entirely. When the valve stem is a non-removable part of the TPMS monitor, this goes from being a minor issue to a critical and often expensive problem.