Common TPMS Questions Answered
Tire Rack's product applications and development team has been actively researching and monitoring the industry's use of tire pressure monitoring systems (TPMS) both prior to and since the November, 2000 enactment of the TREAD Act requiring the use of TPMS on all vehicles built after September 1, 2007. Their fitment specialists have carefully determined which after market wheels, both Original Equipment (O.E.) sizes and Plus Sizes, are compatible with the vehicle and system installed. Search results on Tirerack.com include notes regarding TPMS sensors and sensors can confidently be purchased online with wheels.
But because the National Highway Traffic Safety Administration (NHTSA) provides vehicle manufacturers options with which they can comply with the law (direct vs. indirect systems), there are often questions surrounding proper sensor settings and TPMS parts replacement.
How are TPMS reset?
Unfortunately, one answer will not suffice. For example, a 2006 BMW M3 uses an indirect system with one simple reset button. Once the tires are set to the correct pressure, the vehicle's engine is started and then the reset button is pushed for up to eight seconds. After the warning light turns off, the vehicle is ready to be driven and the system will calibrate itself.
But not all indirect systems are alike. A Buick Rendezvous must be driven at several specific speed ranges, including at 74.5+ mph for 10-20 minutes in a straight line after pressing multiple buttons and turning the ignition key on and off a few times. On the other hand, some direct systems (e.g., the system installed in the Acura MDX) automatically "learn" their new sensors. Other vehicles must be sent to the dealership. Currently, all Hyundai, Infiniti, Kia, Lexus, Mitsubishi, Nissan, Subaru, Suzuki and Toyota models must have their new sensors registered at the dealership. To further complicate things for the aftermarket, Lexus and Toyota models must have each sensor's ID code entered into their ECUs using a dealer-only OBDII scan tool.
| What's the Difference? |
|---|
| DIRECT VS. INDIRECT |
| DIRECT SYSTEMS Attach a pressure sensor/transmitter to the vehicle's wheel inside the tire's airchamber. An in-car receiver warns the driver instantly if the pressure in any one tire falls below a pre-determined level. INDIRECT SYSTEMSUse the vehicle's antilock braking system's wheel speed sensors to compare the rotational speed of one tire vs. the others. If one tire is low on pressure, it will roll at a different number of revolutions per mile than the other three tires, and alert the vehicle's onboard computer. Indirect systems (except for the TPMS on several 2009+ Audi models and 2010+ Volkswagen models) are unable to generate accurate readings in cases where all four tires are losing pressure at the same rate, such as the effects of time and temperature. |
Some systems are becoming a bit more user-friendly, designed to be auto-learn systems or to at least have initialization procedures that can be done at a tire shop or in the customer's garage or driveway with minimal tools.
Questions regarding a specific vehicle's reset procedures can be directed to one of Tire Rack's sales specialists at 800-428-8355.
Do sensors need to be re-registered after tire rotation?
Some systems that display tire pressure per location require a sensor re-learn procedure if the tires are moved to a different corner of the vehicle. Others use antennas in the wheel well to see where the wheel was relocated. If the sensor with the ID code of 1234567 was at the left rear location, but now the left front TPMS antenna is reading the 1234567 ID code, then the system will update its TPMS display to correctly show the wheels and the tire pressures at their new locations. The most common systems only display a low pressure light on the dash and those systems don't normally need to be reset after tire rotation.
When should TPMS parts be replaced?
Every time a tire is removed the sensor must be dropped into the wheel before the tire is dismounted. As a rule, EVERY time a sensor's position is adjusted, the valve cap, nickel-plated valve core, valve nut and rubber grommet seal (and possibly the metal ring found at the base of the valve on many Siemens sensors) must be replaced with O.E. spec parts.
Replacing the rubber grommet helps to eliminate a common source of valve leaks. Never reinstall a sensor without installing a new rubber grommet. And because valve nuts require higher levels of torque, replacing them reduces the chance of failure.
Along with using a calibrated torque wrench on the valve nut, a valve core torque driver should be used when installing a nickel-plated valve core. As a precaution, aftermarket metal valve caps should not be used. Many are made from steel or brass that will corrode an aluminum valve in a short period of time.
Installers should stock replacement parts for their most common applications to ensure they're ready when TPMS installations are performed. TPMS replacement parts kits, sensors, valve caps/cores/nuts and seals are available at Tire Rack.