Rick's Free Auto Repair Advice

Tire pressure sensor replacement

Two types of tire pressure sensing

Carmakers used two types of tire pressure sensing techniques: direct and indirect

Indirect tire pressure sensing

This method monitors the wheel speed sensor to detect the difference in tire revolutions between all four wheels. The system uses the information already available from the wheel speed sensors, so it saves money by eliminating the need for tire pressure sensors.

It’s a theoretical estimation of how much air is in the tires based on the fact that a tire that’s low on pressure will necessarily have a smaller diameter and thus rotate few revolutions than a tire with a higher tire pressure.

Some carmakers used indirect tire pressure sensing up to the 2018 model year. After that, 95% of all carmakers are using direct tire pressure sensors.

Direct tire pressure sensing

In these systems, each wheel if fitted with a tire pressure sensor that monitors the tire pressure and transmits a unique 8-digit identification number and the tire pressure information to a receiver in the TPMS monitor. The dash displays a tire pressure icon when the sensor detects tire pressure that’s 25% less than the carmakers’ recommended pressure for that particular vehicle. In some vehicles, the tire pressure sensor can also transmits the tire air temperature and battery life.

In vehicles that display the tire pressure for each tire location, the tire location is based on the sensor’s unique 8-digit I.D. number. In those vehicles, you must reprogram the TPMS system when you rotate the tires. Otherwise, the dash will incorrectly display the tire pressure location.

3 types of tire pressure sensors

Ford Banded TPMS sensor

Ford’s initial approach to TPMS was to use a regular rubber valve stem and a TPMS sensor, a cradle and a stainless steel band. The sensor is secured to the center of the wheel using the band. The sensor itself is located 180° from the valve stem.

Clamp-in/Bolt-in style TPMS sensor

The clamp-in/bolt-in TPMS sensor is secured to the rim with a nut and seal. The nut must be tightened using a special torque wrench to avoid over-compressing the seal. The seal and nut can be renewed without needing to replace the sensor itself.

Snap -it/Pull-through TPMS sensor

This is a two-piece sensor using a valve stem that pulls through the rim like a traditional rubber valve stem. A brass tube extends into the wheel area and is internally threaded. The brass tube fits into a seal on the TPMS sensor and is secured to the sensor with a screw. The valve stem can be renewed without needing to replace the sensor itself.

All three sensor types have a hole that leads to the air pressure sensor. Tire puncture sealing products can clog the air pressure hole and damage the sensor.

image showing the three different types of tire pressure sensors

OEM TPMS sensors versus aftermarket universal TPMS sensors

OEM TPMS Sensors

OEM TPMS sensors are pre-programmed with the factory software. Each is correct factory frequency and each is programmed with a unique I.D. which must be mated with the TPMS receiver in the vehicle using a special tool.

Aftermarket universal TPMS sensors

Aftermarket sensors come programmed with a unique 8-digit. They must be ordered to match the factory frequency of

314.9 MHz, 315 MHz, or 433 MHz. Each must then be “flash” programmed with the factory software and the serial numbers must be mated to the TPMS receiver in the vehicle using a special tool.

Most aftermarket universal TPMS sensors transmit the basic data of pressure, temperature and battery life. But some do not transmit other unique factory data. In those cases, you must use the OEM sensor.

TPMS modes

TPMS sensor transmit intermittent signals to the TPMS sensor based on which mode they’re in at the time.

Drive mode

The sensor wakes up when it detects wheel rotation and transmits an I.D. number, pressure and temperature at per-determined intervals . In some cases, it can also transmit battery condition.

Park mode

A TPMS sensor will transmit a unique I.D. pressure, temperature at a less frequent interval when the vehicle has been parked for a per-determined amount of time.

Sleep mode

The TPMS sensor will enter a low power sleep mode when the sensor hasn’t detected movement for a per-determined amount of time. This conserves battery life.

Tire pressure sensor replacement cost

Tire pressure sensor replacement cost can run as little as $160 for all four if done with a 4-tire replacement or $$240 or more if done later.

Tire pressure sensor replacement cost is directly related to whether the tire is already removed from the wheel and whether you need an OEM TPMS sensor or can use an aftermarket TPMS sensor.

TPMS battery life averaages 7-10 years. If you haven’t replaced your TPMS sensors in that time period and you’re buying new tires, it makes sense to purchase new sensors at the same time as the tires because the labor to install the sensor is free since the tires are already off the wheel. In this case, many tire shops charge as little as $40 each for new sensors.

However, if you have to replace a TPMS sensor at other times, the shop will have to remove the tire from the wheel, swap in the new sensor and then re-balance the tire. That costs more, as much as $85 per wheel.

If you own a luxury vehicle, you may have to purchase OEM TPMS sensors, which can cost as much as $150 per wheel, raising the tire pressure sensor replacement cost to as much as $800 including labor.

©, 2021 Rick Muscoplat





Posted on by Rick Muscoplat


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