Making Sense of Your TPMS Sensors.

TPMS stands for Tire Pressure Monitoring Systems. This is the system that keeps an eye on the air pressure in your tires and alerts you when any of your tires drop below the acceptable and recommended manufacturers level. It’s an electronic system that connects sensors on the rim to the dash to keep you informed on your air pressure. TPMS sensors first arrived on the scene in the 1980’s on more expensive European vehicles, then in the US later on in 1991 on a corvette. Since 2008, all cars in the US are required to have the sensor installed to help prevent damage to the tire, rim or the TPMS sensor itself. They work as a warning system to help prevent serious damage in the future. Deflated tires can cause larger issues than you think, like accelerated tread wear, decreased fuel efficiency, increased breaking distance and possibly your tire blowing out. A few things that can cause your tires to lose air pressure are warm weather, cold weather, long trips, and debris on the road so it's best to keep an eye on it and check your tire pressure once a month.

This system helps ensure the vehicle performs optimally and keeps the driver updated on any decrease in pressure to quickly prevent any further issues from occurring. When tires are properly inflated it keeps your vehicle performing well by keeping tire wear more even, keeping traction while driving, ensure breaking distance remains shortened, and helps increase fuel efficiency.

All cars, after 2008, have TPMS sensors located inside each wheel attached to the valve stem. They don't incur damage too often since they're secure inside the wheel barrel but there are external ones available, however they are going to be aftermarket pieces. The external TPMS are located by the tire caps and communicate through a digital display in your vehicle to provide real-time tire pressure readings to you.

There are mainly 2 different types of TPMS sensors: Indirect and Direct. They are used for the same purpose, but they operate differently.

Indirect TPMS

An Indirect TPMS uses the same system as anti-lock brakes use so when mounted on the wheels, it doesn't need additional components since it works with the ABS monitor. These types of sensors measure the speed each wheel is turning by an onboard computer and compares the speed with the rest of the wheels and the rate it should be traveling at. The computer system will notice when tire pressure drops by detecting if a wheel is rolling at a varied speed compared to the others and will inform the driver by having the low-pressure light to come on.

Direct TPMS

A Direct TPMS system are going to be the most commonly installed sensor on vehicles. These ones are mounted onto the rim, inside the tire and measures the air pressure in each tire separately. The sensor will notify the computer system with the low-pressure light if the tire pressure drops below the recommended inflation level. They consist of 5 parts: the 4 sensors mounted on the wheel and the indicator for the vehicles computer system.

Direct TPMS vs Indirect TPMS

To summarize, the difference is going to be how the air pressure is monitored on a vehicle. More often than not it is better to go with the Direct system since it's what most vehicles are fit with opposed to an Indirect system where the vehicles owner is going to have to recalibrate it if the pressure changes or when tires are replaced. Another issue with an Indirect system is that it will only alert you if 1 tire is lower than the others but if all are low simultaneously then it will not notify you which can be a bigger issue. So long story short, go with Direct for less headaches with your sensors.

Testing TPMS Sensors

There are a couple of tools shops use to test TPMS sensors, what's used is going to be based on the services needed at that time. For a basic tire service, they will simply check the pressure, usually in a multi-point inspection, so they will use a simple sensor-testing tool (or front-counter inspection tool). This is a fast way to check tire pressure and will let the technician know if the sensor if functioning or not. TPMS sensors can stop working at any time for a variety of reasons but a main one usually is a bad battery. Whenever you're getting them tested at a shop, be sure to ask them to test all sensors to prevent leaving with a bad sensor.
If you're getting more than just a basic servicing like tire rotations, repair and installation, the shop will use a combination style tool (or a TPMS scan tool) since it combines basic sensor testing as well as programming for the sensors. This tool is needed since they will be removing and replacing sensors, so anytime this happens, the new ones need to be programmed and re-learned to the vehicle.

When to Replace a TPMS Sensor

The most common damage that occurs to TPMS sensors is going to be corrosion, batteries running down on them, or damage from everyday driving issues that occur like a flat tire or hitting a pothole. Since TPMS sensors are electronic, they run on batteries and while they have a battery-saving operating system they do have a limited lifespan and typically can run for 5-10 years, depending on the type of sensor. If you do have a damaged TPMS sensor, unfortunately you will need to replace it since they are unrepairable.

Replacement Sensors

Direct Replacement

This sensor requires a TPMS tool to complete the relearning process, configuring, and programming. It is a factory equivalent part to the original sensor the wheels first come with so it will be a “part for part” fitment and can come directly from the factory or there are aftermarket versions available.

Multi-protocol

This sensor needs a TPMS tool to have it relearn the process but unlike a direct replacement, it doesn't need a tool to prep any more than that. This sensor is a direct replacement for the original part except as the name implies, its one sensor that houses multiple sensor output protocols which means it can cover a wider range of the original part numbers.

Programmable

This sensor requires a TPMS tool to program them prior to installation. There are 2 types of programming; Wireless, which uses a low frequency signal from a TPMS tool to configure the sensor and the other is contact programable which means its non-wireless and programmed through direct contact. Since they're programmable, you get the latest coverage, and they tend to cover a wider range of the original part numbers. When programming these sensors, they range in the way they're set up by either doing a simple sensor ID copy to a complete protocol ID setup.


As you can see from all the information above, deciding on the right TPMs sensor and servicing them can get confusing since there's many options out there and sub options in those options! The following FAQ’s might confuse you more or help answer and provide better clarity, hopefully it's the latter.

Frequently Asked Questions (FAQ)

Why Are TPMS Sensors Required?
• In 2000, the TREAD (Transportation Recall Enhancement Accountability and Documentation) Act was passed. This Act requires all new cars sold in the US after September 2007 must be equipped with TPMS. The TREAD Act was pushed for approval mainly due to the Ford and Firestone Tire controversy. This was a three-year period in which tire tread separation and failure was traced back to over 271 fatalities and over 800 injuries in the US.

Are TPMS Sensors Required by Law?

• Yes, the United Stated Congress legislated the TREAD Act, which requires all light motor vehicles to be equipped with a proper TPMS sensor. As of 2008, all new passenger vehicles must have a TPMS sensor installed. For trucks and vans, a TMPS sensor is not mandatory.

Can You Drive With A Broken TPMS Sensor?

• The vehicle can be driven when the TPMS sensor is broken, but it is recommended to have it fixed as soon as possible. If the TMPS sensor is not doing its job correctly, you will not know when the tires lose air pressure. This can lead to damage to the tire, the rim, and the vehicle if you are not careful.

How Much Does It Cost to Replace A TPMS Sensor?

• To replace a TPMS sensor, will typically cost you between $220 and $240. The price to replace the parts needed for the TMPs is around $170 and you will need to add the labor cost, which is usually between $50 to $70 depending on where you take your vehicle.

What Does It Mean When A TPMS Light Comes On?

• When the tire pressure monitoring light turns on, it means the tire or tires have lost air pressure. In such instances, the tire pressure runs lower than what is recommended, and it needs to be fixed to ensure the vehicle's performing security. If your tires run on low pressure for extended period damages will occur. Noticeable changes such as folding of the sidewall and damage the tire to the point of irreversible damage.

-Heather Jarkow