TIRE BASICS

Understanding Your TPMS Sensor

What Does TPMS Mean?

TPMS stands for Tire Pressure Monitoring System. This system provides the driver a visual indicator on the dashboard if it recognizes a substantial variance in tire pressure from the vehicles recommended placard pressure value.

Where is the Tire Pressure Sensor Located?

Typically, each wheel on your vehicle has a tire sensor mounted on the inside of the tire. Many vehicles use a specially designed tire valve that has the sensor integrated. Other vehicles may have the pressure sensor mounted to the inside of the wheel.

Since the 2005 vehicle model year, tire pressure monitoring systems have been gradually added as standard equipment – and was mandated by federal law starting September 1st, 2007.

A quick way to know if your vehicle has a TPMS installed, is to start your vehicle and then look at the dashboard for a TPMS light to illuminate briefly.

How Do Tire Sensors Work?

Most commonly, each tire pressure sensor has a small battery inside that powers the sensor, as well as a wireless transmitter. The sensor periodically checks the tire pressure and temperature and sends the readings to the computer within the vehicle.

If the vehicle is not moving, the sensors go into a sleep mode to conserve the battery within. Even during sleep mode, some systems will periodically activate and transmit the temperature and pressure data to the computer.

What Does the TPMS Light Indicate?

If you notice the TPMS indicator light staying on for a few seconds after startup, that indicates proper function of the TPMS system. However, If the light stays on after that few seconds, the vehicle is trying to tell you that there could be an issue with the air pressure in one of your tires.

When the TPMS light is staying on without flashing, it means that one or more of the tires on the vehicle is underinflated by 25% of the pressure listed on the door placard. This could be the spare tire, too – so when you go to check the tire pressure after the TPMS light starts glowing, also check the spare.

If, conversely, the TPMS light is flashing continuously for about 60 to 90 seconds, that generally indicates that there is a fault within the tire pressure monitoring system itself. Further diagnosis of the tire pressure monitoring system is required.

Remember that both your vehicle’s owner’s manual and the tire pressure placard (found inside the driver’s door jamb), are the authority on your vehicle’s ideal tire pressure. Check your tire pressures when the tires are cold as the friction of driving can cause the pressure to fluctuate. Don’t inflate your tires to the pressure listed on the tire itself – that is the maximum pressure for the tire.

What Happens to the Tire Sensor When Tires are Serviced?

If your tires have been removed from the vehicle – either for tire repairs, replacement, or a simple tire rotation, the TPMS may need a reset or recalibration depending on the system. If the vehicle loses power – say, if the vehicle battery is being replaced – the TPMS may need recalibration or reprogramming as well.

When a tire is being removed from a wheel for repair or replacement, it is a best practice to service the TPMS sensor. Depending on the type of sensor, this may require replacement of the locknut, gasket, valve core, and potentially the valve cap.

Specialty tools are generally required for these services. Your Goodyear Tire & Service Network location can properly manage your TPMS service, which should be done any time you are replacing your tires.

Do Spare Tires Have TPMS Sensors?

Some vehicles do indeed have tire pressure sensors in the spare tire. A Goodyear technician can help you determine if your spare tire is equipped with TPMS. It’s always a good idea to check your spare for proper pressure periodically – you never want to be stuck on the side of the road with a flat tire on the vehicle only to find that the spare tire is flat as well.

What are the Different Types of Tire Pressure Monitoring Systems?

There are three main types of tire pressure monitoring systems offered today:

Direct TPMS: Direct systems monitor the pressure and temperature from within the tire using actual sensors to communicate with the vehicles on-board receiver.
Indirect TPMS: Indirect systems does not use a physical pressure sensor within the wheel to monitor the individual pressure, but in fact uses the vehicles ABS system to measure the rotational speeds of each tire. Minor tire pressure differences can cause one or more of the tires to rotate at a different rate than the others which is detected by the system and will cause the TPMS light to turn on. Defective wheel speed sensors or driving in slippery conditions can also cause the TPMS light to turn on with this type of system.
Hybrid TPMS: Internal tire sensors work in conjunction with wheel speed sensors to help tell the driver (via a dashboard indicator) which tire is underinflated.

As always, if you have any questions about your tire’s monitoring system, don’t hesitate to call your local Goodyear Retailer.