How to Guides

When To Adjust or Replace TPMS Sensors

Zaki Moulvi posted this on Jun 9, 2014

The tire pressure monitoring system, or TPMS is a relatively new automotive technology that became standard on all vehicles sold in the US after September of 2007.  As the critical nature of correct tire pressure became apparent to law makers, they put into effect the TREAD act, which not only mandates the use of TPMS sensors, it also ensures that automobile manufacturers follow a specific protocol in the event of a major recall.  All of this was in response to the late ‘90’s Firestone tires tragedies, whose tread separation was responsible for over a 100 deaths related to roll over accidents.

Indirect TPMS Sensors

An indirect TPMS does not measure the physical air pressure inside of the tire.  Instead, it monitors the speed of the tire to determine if it is inflated to the proper pressure.  Mounted outside of the tire in the wheel hub assembly, these systems use the already in place ABS sensors to obtain the necessary.  While the accessibility and ease of use is appealing to car owners, this method is viewed as unreliable and not found on many automobiles.

Direct TPMS Sensors

Direct TPMS places the sensor inside of the tire where it is able to directly gauge the tire pressure.  Each wheel is equipped with its own sensor, allowing your cars engine control unit to monitor all four tires at once.  The drawback in the design of these sensors is their battery operation which necessitates changing them out when the battery loses power.  Most direct TPMS technology is designed to employ the sensor only when the tire is rotating, thus conserving the life of the battery as well as the battery of the sensor located in your spare tire.

Monitoring

In order for TPMS to work, the driver has to be alerted when the sensor detects a dangerous decrease in the air pressure of a tire.  This is done using your vehicles ECU and a dashboard light.  When the ECU reads that a tire is in need of air, it will illuminate the light, and keep it lit until the problem is resolved.

Adjusting Your TPMS

The TPMS sensors that come with your vehicle have been pre-set to work with your cars ECU.  In some instances, any changes to air pressure will require that they be reset.  Some vehicles will have an easy to access reset button while others will entail accessing the computers menu.  In either event it will take anywhere from 20 to 60 minutes of driving after a reset for the ECU to make the adjustments for your tires parameters.   Consult your owner’s manual anytime you add air to a tire or make any other adjustment to ensure that the TPMS sensor is still able to read it accurately.

Replacing A TPMS Sensor

As mentioned above, the sensors reading your tire pressure are being run on a battery which cannot be replaced.  Once that battery has run out of voltage, the entire sensor will have to be changed.  Another cause of TPMS sensor failure is trauma to the tire. This could be the result of an accident or even a sharp impact with a curb.  The dash light should alert you when one of the sensors is no longer giving the ECU any readings. 

Since all four TPMS sensors were installed at the same time, it should be safe to assume that all four batteries will give out around the same time, so if you are needing to replace one, it makes sense to do them all together.  Purchase your replacement sensors on-line at CarPartKings.com to ensure you are paying the lowest possible price.  Buying them through your dealer will easily empty your wallet.

Replacing the TPMS sensors involves deflating the tires to remove the old ones and reinstall the new ones.  Since you will then need to balance your tires, it is recommended that you have the sensors replaced at your local mechanic shop or tire store. 

Do I Have to Replace the Sensors?

Using a TPMS is now mandatory on all vehicles, so the short answer would be yes.  Considering the importance of tire pressure to your safety and that of your passengers, you should be grateful for the technology.  Most vehicle owners do not check the pressure inside of their tires often enough.  Under-inflated tires will wear out faster, making it difficult for you to maintain traction with the road.  The uneven wear pattern in the tread will also make you more susceptible to a blow out.  To avoid either of these scenarios it is best to keep functioning sensors inside of your wheels.

If you aren’t sure if you have a TPMS in your vehicle or if it is working properly, bring your car to a mechanic for a check-up.  These little sensors go a long way in protecting you.