TPMS Sensor

Tyre Pressure Monitoring System sensors are battery-powered radio frequency transmitters mounted inside each wheel — either on the valve stem or banded to the rim — that continuously measure tyre pressure and temperature and transmit readings to the TPMS control module. Direct TPMS systems use individual pressure sensors at each wheel; indirect TPMS systems use the ABS wheel speed sensors to detect inflation loss by measuring the faster rotation of an underinflated tyre (which has a smaller rolling circumference). Direct TPMS sensors transmit at 433 MHz or 315 MHz depending on market, with each sensor having a unique ID code that the TPMS module learns during calibration. Sensor batteries are non-replaceable sealed units lasting 5–10 years. When a tyre drops 0.2 bar or more below the vehicle's set pressure, the TPMS warning light illuminates on the dashboard — a solid light for a current low-pressure condition, a flashing light (60 seconds then steady) for a system fault.

TPMS provides continuous real-time monitoring of tyre inflation and alerts the driver to pressure loss before it reaches dangerous levels — addressing the human tendency to neglect monthly pressure checks. A tyre at 0.3 bar below specification has already increased fuel consumption, begun accelerating shoulder wear, and reduced wet-weather braking performance — changes that are imperceptible to the driver without measurement. TPMS is legally mandated on new passenger vehicles in the EU from 2014 and in the US from 2008 precisely because tyre pressure neglect is a leading cause of blowout-related accidents. The system is particularly critical on run-flat tyres, which do not provide physical deflation feedback to the driver. TPMS does not replace monthly manual pressure checks — the 0.2 bar warning threshold means a tyre can be consistently at 0.1–0.19 bar low without triggering any warning.

TPMS warning light appearing after seasonal tyre change: New wheels fitted with different TPMS sensors (or no sensors) that have not been registered to the vehicle's TPMS module. The module does not recognise the sensor IDs. Relearn procedure required — either automatic (driving at speed for the module to learn new IDs) or manual (using a TPMS activation tool to trigger each sensor in the module's programming mode).

TPMS warning light after correct inflation: Sensor battery has depleted (end of service life), sensor damaged by impact during tyre mounting, or sensor corroded and transmitting intermittently. Read fault codes to identify which sensor position is reporting the fault.

TPMS light flashing for 60 seconds then staying on: System fault rather than a low-pressure event. The flashing pattern specifically indicates a TPMS module or sensor communication fault — distinguishing it from a simple low-pressure warning.

Level 1 — Owner check: Monthly pressure checks remain necessary despite TPMS — the warning threshold of 0.2 bar allows tyres to run consistently low without triggering an alert. Understand the two TPMS light patterns: steady = low pressure (check all four tyres immediately); flashing then steady = system fault (requires diagnosis).

Level 2 — Detection: When fitting seasonal tyres or replacement tyres, confirm that TPMS sensors are present on each wheel and registered to the vehicle. A missing sensor is a safety and legal compliance issue. Inspect sensor valve stems during each tyre change for corrosion — the aluminium valve stem corrodes where it contacts the steel rim, eventually causing the valve to break during tyre demounting.

Level 3 — Professional service: TPMS sensors require replacement at end of battery life — the battery cannot be replaced independently. Replace sensor valve stem seals (O-ring and valve core) at every tyre change — these seals prevent air leakage around the sensor valve and degrade with heat cycling. Use a TPMS relearn tool after any sensor replacement to register the new sensor IDs to the vehicle module.