Tire Pressure Monitoring System Sensor

What are tire pressure monitoring system sensors and where are they located?

The tire pressure monitoring system (TPMS) is an important safety feature on newer cars, trucks, and SUVs. This system measures, identifies, and warns drivers if their tire pressure becomes too low, identified as a certain percentage or more below the manufacturer’s recommended pressure level, and that air is needed. Low tire pressure increases the risk of rollovers and increases braking distance, and it can also negatively affect performance and fuel mileage. After a string of fatal accidents in the 1990s involving failing tires, legislation was put into place that would eventually require TPMS on all new vehicles that warn the driver when a tire, or tires, are underinflated—and dangerous. By calling attention to an underinflated tire or tires, the system essentially prompts the driver to inflate the tire to the proper psi level before catastrophic tire failure occurs. As of 2008, all new vehicles sold in the United States were required to be equipped with tire pressure monitoring systems.

There are two main types of systems used to monitor the air pressure in tires: indirect and direct. Instead of measuring the actual pressure in the tire, an indirect TPMS uses the sensors in the wheel hub assemblies (usually the ABS wheel speed sensor) to measure differences in wheel rotation speeds. A tire with lower pressure would be smaller in diameter and make more rotations than the same size tire with proper air pressure. A difference in rotation speeds indicates low pressure in one tire. One weakness of these indirect systems is the inability to recognize if all four tires have low pressure. These types of systems also don’t tell the driver which tire exactly is low on pressure.

Direct sensor systems use dedicated TPMS sensors. In direct sensor systems, each tire uses a small battery-powered sensor to measure the amount of air pressure in the tire. This measurement is transmitted by radio to a receiver in the vehicle, which gives the reading to the vehicle’s onboard computer. The sensor may be at the base of the valve stem, or attached to the middle of the wheel rim. 

In either direct or indirect tire pressure monitoring systems, there is a display in the dash that warns the driver if tire pressure has gotten too low. This may be a diagram of the four tires, where the tire with low pressure will be lit up. It may also be a simple light that shows the cross-section of a flat tire (it sort of looks like a horseshoe) with an exclamation mark inside it. That light will come on if one or more tires have low pressure. 

How do I know if my tire pressure monitoring system sensors need to be replaced?

Fortunately, your tire pressure monitoring system sensors will tell you if they need to be replaced. If the sensor only sent a signal when the tire pressure got low, a failed sensor wouldn’t affect the system. Then a driver might think that their tire pressure was fine, when in fact it was not. For this reason, the sensor periodically sends a signal to the receiver to indicate that the sensor is working. If this signal isn’t received, then the computer will recognize that one of the sensors has failed. In this event, it causes your tire pressure dash light to flash on and off. This flashing light is your warning that one of your tire pressure sensors is not working. 

The most common cause for TPMS sensor failure is a dead battery in the sensor. Each sensor carries its own battery, and even though the lifespan is quite long, they eventually run down like any other battery. The battery itself cannot be replaced so the whole sensor has to be. Sensors installed in the first couple years of the TPMS requirement are beginning to reach the end of their lifespan. The battery can run more quickly if it has to transmit frequently—that is to say, if you run on low tires a lot or for a long time. 

The sensor can also be damaged if you hit the curb or a large pothole. This will necessitate replacement of the whole sensor. Also, keep in mind that even if you have a tire pressure sensor, it’s important to check your air pressure regularly.

Can I replace TPMS sensors myself?

Unfortunately, replacing your TPMS sensors requires some assistance from a professional technician. The tire will have to come off the rim to make it possible to access the sensor. This will require the use of a tire machine. Once the sensor has been replaced, the vehicle’s computer will have to be reset to recognize the signal from the new sensor, which requires the use of highly specialized electronics. This process, and the necessary equipment, vary from one model to the next so procuring them is out of reach for the average driveway mechanic. Without resetting the system, the TPMS system dash light will continue to flash, and the TPMS won’t function. 

Need a tire pressure sensor replacement?

Have you ever seen a vehicle with one or more tires that appear noticeably low on tire pressure? Didn't you want to somehow let the driver know before that slight inconvenience turned into a calamity? What if the vehicle with the low tire pressure was the one you were driving? Wouldn't you want to be warned in case you may not have noticed the last time you checked your tires? Let’s face it – despite the fact that everyone should regularly inspect their tires to make sure they have the proper levels of air pressure in them, many people simply neglect to do so. Thankfully, tire pressure monitoring systems are now required in all vehicles in order to warn drivers of low tire pressure and avoid dangerous situations that can result. Here at 1A Auto, we carry a large selection of replacement tire pressure monitoring system sensors for many makes and models if the ones in your vehicle are no longer functioning.

We also make shopping for replacement tire pressure monitoring system (TPMS) sensors for your car, truck, SUV or van easy here at 1A Auto - we're here to help you select the right part for your vehicle! Call our customer service toll free at 888-844-3393 if you have any questions about our TPMS sensors, warranty, compatibility or to purchase, or you can buy online.