Most vehicles sold in the United States are equipped with a safety feature known as the Tire Pressure Monitoring System (TPMS). The reason for their existence dates back to 2007, when the government passed legislation requiring their use in response to a surge in accidents caused by under-inflated tires. The purpose of the TPMS is to alert you when one or more of your vehicle’s tires is significantly under-inflated. In this blog post, we will discuss how the TPMS works and what to do when the tire air pressure warning light comes on.
How does the TPMS work?
Your vehicle is equipped with one of two types of tire air pressure monitoring systems – indirect and direct.
- An indirect TPMS doesn’t actually measure the air pressure in your tires. Instead, wheel speed sensors gauge the rate of revolution for each wheel and send the data to the on-board computer system. The computer uses the data to determine the relative size of each tire. When one or more wheels start to spin faster than expected, the system alerts the driver that the tire is under-inflated and triggers the warning light for the TPMS.
- A direct TPMS utilizes actual sensors within each of the tires to monitor the air pressure. Just like the indirect system, the sensors are sending information to the on-board computer. If the system detects low tire air pressure, the computer will turn the tire pressure warning light on. In a direct TPMS, the tire sensor is sending all of its data to the computer wirelessly. Each sensor also has a unique serial number that allows the system to distinguish between the different tires. When you replace your tires, the tire pressure sensors must be reset for the system to operate properly.
The Tire Air Pressure Warning Light turned on, what do I do?
The answer to this question depends on when the light came on:
- If the light came on when you were driving, you should find a safe place to pull over and check the tires. A nail or piece of debris could have punctured the tire and it is losing air quickly. If there doesn’t appear to be a flat tire, check the air pressure in each tire using a tire gauge. If the air pressure in each tire is fine, the light could have been triggered by a problem with the Tire Pressure Monitoring System.
- If it was cold outside and the light came on in the morning or after several hours of your vehicle sitting, you will need to check the tire pressure and add air to one or more of your car tires. When it’s cold outside, the tire air pressure will be lower than when it is warmer outside. If the pressure goes below the threshold for the TPMS, the air pressure warning light will come on. When adding air, make sure you fill it to the recommended air pressure found on the label inside the driver’s side door.
Quick Tip: On some vehicles, The TPMS Warning Light will need to be reset once you add air to the tire(s). This can be accomplished by pressing a reset button on your instrument panel.
The TPMS light won’t turn off (or it came back on). Now what?
If you added air and the light stays on, first check to see if you need to reset the TPMS warning light on your instrument panel (if equipped with this feature). Typically, a light that won’t turn off indicates there is either a bad pressure sensor in one or more of the wheels, one of the batteries in the tire pressure sensor has gone bad, or there is an internal fault in the system. You will need to replace the tire pressure sensor.
In some cases, the light will come back on because you have a slow leak in your tire. This can be quickly confirmed by checking the tire pressure using a tire gauge. In this case, you will need to either have the tire repaired or replaced.
Quick Tip: For an Indirect TPMS, if the light comes on and stays on, there may be a faulty wheel speed sensor. Typically, if this is the case, the ABS Warning Light will also come on.
Luke’s Auto Service in Verona, NJ can handle all your tire needs.
Whether you have a tire air pressure warning light that won’t go off or you need to have a tire repaired or replaced, Luke’s Auto Service can assist you. We have all the necessary equipment to diagnose and fix a problem with the TPMS. If you need to replace your tires, we carry a wide selection of tire brands. Contact us today for all your vehicle needs.