TPMS sensors: how long does the battery last and when do they need replacing?

Which cars have TPMS sensors in the wheels?

Only cars with direct TPMS have sensors in the wheels; those with indirect TPMS use the ABS sensors and have no components in the wheels.

TPMS has been compulsory on all new cars registered in the EU since 1 November 2014, but the manufacturer can choose the type of system. The difference between direct and indirect, and what to do when the warning light comes on, is explained in the guide on the tyre pressure warning light: here we focus on the sensors.

A practical clue: if the dashboard shows the pressure of each individual wheel, the system is almost always direct.

How long does a TPMS sensor battery last?

A TPMS sensor battery normally lasts several years, but its actual life depends on the sensor, the mileage and the conditions of use: there is no single figure that applies to all.

In most sensors the battery is built in and sealed: when it runs out, the whole sensor is replaced. Because a car's sensors are fitted at the same time, they may run out within a short time of each other.

How can you tell if a TPMS sensor has failed?

A failed or flat sensor can be recognised because the system reports a malfunction rather than a pressure drop: on many vehicles the warning light flashes for a while at start-up and then stays on, or an error message appears.

• The pressure for one wheel is no longer shown on the dashboard.
• The warning light stays on even after you have checked and corrected the pressure.
• The problem appears after a wheel or tyre change.

The exact behaviour varies from manufacturer to manufacturer: check the manual. Until the system is working, check the pressure manually, as explained in how to check tyre pressure.

What happens to the sensors when the tyres are changed?

When the tyres are changed, the sensors normally stay on the wheel rim and must be handled carefully while the tyre is removed and refitted.

1. Whoever does the work needs to know the wheel has a sensor, so as not to damage it with their tools.
2. At a tyre change, the valve's sealing parts (seals, nut, valve core) are often replaced, following the sensor manufacturer's instructions.
3. After fitting, some vehicles recognise the sensors by themselves after a short drive; others need a relearn procedure.

If you use two sets of wheels (summer and winter on different rims), the second set must also have compatible sensors, otherwise the system will report an error.

TPMS sensors and puncture repairs

A TPMS sensor does not prevent a puncture from being repaired, but it needs to be taken into account before starting work.

• Some sealants in emergency kits can foul the sensor: after using one, tell whoever checks the tyre that you used the kit (see how to use the tyre repair kit).
• To repair from the inside, the tyre must be removed from the rim, taking care around the sensor's position.
• On run-flat tyres, TPMS is essential: read run-flat tyres: how they work.

Warning light on and a low tyre in Milan?

If the warning light is reporting a real drop and a tyre is low or flat, the problem is the tyre, not the sensor. In Milan and its province, SOS Tyre comes out 24/7, in 30 minutes on average, to wherever the car is, including vehicles with TPMS and run-flat tyres.

Call +39 377 326 0999 or fill in the request for assistance.