While tire technicians have been dealing with broken sensors and corroded valve stems since tire pressure monitoring systems (TPMS) became a federally mandated feature on all U.S. passenger vehicles since the 2008 model year, another issue is looming—sensor battery exhaustion.
The batteries in the closed-system sensors are expected to last five to seven years or 50,000 to 70,000 miles, but several tire dealers Tire Business spoke to said they haven't seen a high rate of battery failure—yet.
There are more than 75 million TPMS-equipped vehicles in North America with an estimated 300 million installed sensors, according to Schrader International Inc., a TPMS sensor maker. The company referred to an independent study that forecast that the amount of sensor replacements due to battery expiration is expected to increase over the next few years.
“We're not seeing a tremendous amount of failing of batteries at this point,” said Dominic Umek, general manager of Cleveland-based Conrad's Tire, echoing several tire dealers' comments on the subject.
“I think the original estimate time of battery life was a little aggressive and now they're finding that real world usage is probably not quite so optimistic,” said Kevin Rohlwing, senior vice president of education and technical services for the Tire Industry Association (TIA). “Originally they were talking 10 years/150,000 miles, and it's turning out to be less than that. And it depends on a lot of factors, but it definitely isn't turning out to be what they thought it was.
“We haven't heard a lot of complaints from dealers about it,” Mr. Rohlwing added. “I'm sure consumers are going to be the ones to complain about it the most. For the dealers themselves, it's an opportunity for them to sell them new sensors. So it's probably not as big of an issue for them but certainly there are a lot of consumers out there that were expecting those batteries to last longer.”
Mr. Rohlwing said sensor batteries appear to be lasting until the second, or even the third set of tires mounted on a vehicle.
“A general guide on battery life is 10 years or 100,000 miles as an OEM-designated specification. However, individual battery life varies from vehicle-to-vehicle based on individual driving behavior and driving patterns,” according to Paul Wise, director of product management and marketing for Schrader. “When the vehicle is in motion, the sensor will transmit more frequently (typically once per minute) than when not in use. So if a vehicle is driven heavily, the sensor battery life will, of course, be consumed faster than a vehicle driven only occasionally.”
TPMS sensors may be covered under the OE manufacturers' vehicle warranty and possibly an extended warranty.
“We encourage a pre-service check, period,” TIA's Mr. Rohlwing said. Technicians should assess if the TPMS is operational when the vehicle enters the shop and before it leaves.
If a system is inoperable before it gets to the dealership, “that needs to be documented and communicated to the customer so that the customer has the option of paying for the repairs or not paying for the repairs—but the dealer is not responsible,” he said.
Some TPMS batteries indicate only whether they are working or not while others provide an indication of the battery power level. Some sensors can transmit battery life readings to certain handheld scan tools.
“You can assess the status of the sensor power by looking at how many miles are on the vehicle and how long they've had the vehicle,” Mr. Rohlwing said. “Certainly, if you've got a vehicle that's over five years old and over 100,000 miles on the original sensors, then you're probably looking at a system that will start failing in the near future.”
According to Schrader, sensors should be replaced when inoperable but not on a specific interval if still working. However, if the mileage of the vehicle is close to the 100,000-mile mark, “it is worth suggesting to the vehicle owner that all four sensors can be replaced at once so as to save them time. The benefit is that the owner does not have to return to the shop several times to replace sensors as they electronically fail due to end of battery life,” Mr. Wise said.
“The key for service and repair facilities is to ‘test before you touch,' which means identifying the health status of each sensor (using a handheld tool) prior to doing any work on the vehicle,” Mr. Wise said. “This will allow the technician to relay to the consumer what TPMS-related action needs to be done and why. This will help the consumer understand what's being done, why it's important, and soften the reaction to the cost of this repair.”
“We recommend, due to the battery life being between five years or 50,000 miles, whenever a retail tire store examines a vehicle that has original sensors in it and it exceeded those two numbers, that they replace the sensors,” said Russ Fuller, president of Revolution Supply Inc., maker of Oro-tek aftermarket TPMS sensors. “It will alleviate them from having to pay for a new mount and balance if their sensors go defective within the life of the new tires they're putting on the vehicle.”
Schrader promotes the use of its service packs when servicing the TPMS during tire changes and rotations. The company said each time a clamp-in sensor is removed from the rim hole, the grommet, nut, nickel-plated core and cap should be replaced. Snap-in sensors also should have their valves replaced each time the sensor is removed from the rim hole.
“The snap-in sensor valve should be replaced just as a standard valve stem is today,” Mr. Wise said.
The reasons service pack replacement is “critically important,” according to Schrader, include:
* Rubber grommets replace old seals that may have taken permanent compression set;
* The valve stem nut replaces the old nut which may have damaged threads caused by over-torqueing or other mistreatment;
* Nickel-plated valve cores are used to prevent galvanic corrosion between non-similar metals (brass and aluminum), causing a brass core to seize into an aluminum stem;
* The valve cap with seal prevents dirt and moisture from entering the sensor and also acts as a secondary pressure seal. Old valve caps may have a seal that is compressed set or missing; and
* The washer replaces the old washer, which may have been deformed during initial installation.