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Dry Braking

TPMS-the why and wherefores

Since November 2014 and any new vehicle in the EU must have a tyre pressure safety device fitted. Here’s the lowdown.

 

All new cars in the European Union must be supplied with TPMS and this is now being tested as part of the MOT road worthiness test. Any vehicle that originally had TPMS fitted as standard, will fail an MOT test if it has been removed or is found to be faulty.

 

WHAT ARE TPMS SENSORS?

TPMS sensors are a safety device that monitor tyre pressure and are designed to alert the driver to an under-inflated tyre. Having the correct tyre pressure avoids excessive fuel consumption and wear and tear. Scientific research shows that driving a vehicle with a tyre pressure of 0.2 bar too little leads to 5% more urban fuel consumption.

In an indirect system, ABS sensors can calculate tyre pressure incorrectly by measuring the wheel speed. In a direct system, TPMS sensors are installed internally on each tyre valve to measure the exact air pressure and temperature directly at the valve of each tyre. Every sensor has a unique identification, which it transmits to a receiver via wireless remote frequency at 433 MHz (Euro standard). The receiver then transmits the data to the vehicle’s on-board system and warns the driver immediately if the tyre pressure decreases below the ideal level for their tyre.

 

FAULTS AND REPLACEMENT

TPMS sensors are powered by an internal battery that cannot be replaced because the sensor is filled with a stabilising gel material to cushion and protect the sensitive elements inside. The battery life is around 8 to 10 years, dependent on annual mileage.  

Sensor valves normally require replacing after around 5 years or a mileage of 100,000 miles as they weaken with time and usage.

With every transmission of data, the sensor will also send a battery state signal, which workshop tools can use to diagnose a low battery. In addition to the regular wear, a mechanical defect such as corrosion on the valve can lead to faults within the TPMS sensor.

 

 

 

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