A tire pressure monitoring system, or TPMS, sensor lives inside each tire and measures the air pressure directly. When a tire drops below a safe threshold, the sensor radios that information to the vehicle, which lights the low pressure warning on your dash. Direct TPMS sensors keep you informed without you having to check each tire by hand.
Animated: how a TPMS Sensor actually works
🔧 How It Works, Step by Step
1
Sense the pressure
A small pressure transducer inside the sensor measures the air pressure and often the temperature inside the tire.
2
Package the data
A tiny circuit board reads the pressure and pairs it with a unique sensor ID for that wheel position.
3
Transmit wirelessly
The sensor sends a radio signal, typically on 315 or 433 megahertz, to a receiver in the vehicle.
4
Warn the driver
The vehicle module compares the pressure to a threshold and lights the low tire warning if any tire is underinflated.
🧩 The Key Parts
Pressure transducer
Measures the actual air pressure inside the tire.
Radio transmitter
Sends the pressure reading and sensor ID to the vehicle receiver.
Battery
A sealed lithium cell that powers the sensor for roughly five to ten years.
Valve stem body
Mounts the sensor to the wheel and serves as the tire valve.
📋 Free OBD2 Code Cheat Sheet
The 50 most common check engine codes with likely cause and DIY fix cost. Sent once.
🩺 Signs of a Failing TPMS Sensor
TPMS warning light on
TPMS light flashing then staying lit
No pressure reading for one wheel
Warning light after a tire rotation
Repeated false low pressure alerts
Light stays on after inflating tires
⚠️ Common Problems
Dead sensor battery
The sealed battery cannot be replaced, so the whole sensor must be swapped when it runs down after several years.
Corroded valve stem
Aluminum valve stems corrode and can crack or leak, sometimes damaging the sensor.
Unregistered sensor
A new or rotated sensor may need to be relearned to the vehicle or it will not report correctly.
💰 Cost to Fix
$80-$200 per sensortypical range to repair or replace, parts and labor
❓ FAQ
Can a TPMS sensor be repaired?
The valve core, cap, and grommet can be serviced, but if the internal battery dies the entire sensor must be replaced.
Do I need to relearn sensors after a tire rotation?
Many vehicles need a relearn so each sensor is matched to its new wheel position, though some detect positions automatically.
How long do TPMS sensor batteries last?
Typically five to ten years depending on how much you drive and the temperatures the sensor sees.