Tyre pressure monitoring systems (TPMS) guide - all you need to know

Tyre pressure monitoring systems (TPMS) are a key safety feature. They monitor the air in your tyres and warn you if the level of pressure drops too low.

All new cars are fitted with a TPMS by law, although the way the system operates can differ. There are also some occasional problems and warning messages that you should look out for, as these may suggest a technical problem with your vehicle.  

Whether your car has a TPMS system or not, it’s important to manually inspect your car's tyre pressure regularly, too.

We recommend checking your tyres when they are cold, allowing four hours to pass after driving to get the most accurate reading.

In this car maintenance guide, we look at how TPMS works, servicing requirements, and how a faulty tyre pressure monitoring system can result in a failed MOT.

What is a (Tyre Pressure Monitoring System) TPMS?

The tyre pressure monitoring system (commonly known as TPMS) is an onboard safety feature designed to track the air pressure inside your car’s tyres.

If the air pressure drops below a safe level, the TPMS will trigger a car dashboard warning light that will inform you of a potential problem with the vehicle’s wheel or tyre.

How does a (Tyre Pressure Monitoring System) TPMS work?

TPMS has been fitted as standard on many modern vehicles since 2012. There are two TPMS systems that are commonly found on cars:

• Direct: this TPMS system uses direct sensors inside each wheel to measure tyre pressure

or

• Indirect: the ABS system is used to measure the rotational speed to calculate the tyre’s pressure

Common TPMS problems

The TPMS can suffer from a wide range of problems – they typically arise from sensor wear or issues within the vehicle’s electronics.

They can also suffer from general wear and tear, meaning that they need to be replaced every few years.

One of the most frequent issues is battery failure inside the TPMS sensors.

Unfortunately, these batteries are sealed and non‑replaceable, usually lasting up to 10 years, and when they weaken, the system may produce a warning for the driver.

Another common problem involves damaged or corroded sensors, often caused by exposure to moisture.

This can often lead to inaccurate pressure readings or complete sensor failure.

Faulty sensor readings can also occur when tyres are over or under‑inflated just enough to trigger warnings, even if the tyre is not punctured or suffering from any form of damage.

If the car’s onboard ECU is having issues, it can sometimes trigger false warning around tyre pressure.

Do TPMS valves need servicing?

Yes, TPMS valves require regular servicing.

As a vital part of vehicle maintenance, it should be something that you service or replace every time you fit new tyres to your car.

This is because the valves wear out over time, and so can the sensors themselves, which may result in incorrect readings and increased risk of safety issues.

Will my car fail the MOT due to a faulty TPMS?

Yes, your car will fail the MOT if there is an issue with the TPMS.

TPMS checks were added to the MOT test in 2015 – and if the TPMS warning light is on, this results in an instant MOT fail.

This is why keeping your TPMS and tyres in great condition is important, as it avoids the risk of unexpected failures.

Is TPMS a legal requirement?

Yes, a TPMS is a legal requirement for all new vehicles in the UK. It is also a legal requirement that the TPMS must work if it is fitted to the vehicle.

Can I drive with the TPMS light on?

It is not illegal to drive with the TPMS dashboard warning light on, but it is not recommended to travel far with it illuminated, as you may have a puncture or fault with the wheel or tyre.

If your car has a TPMS system, it must be working correctly.

You are responsible for ensuring your car is always safe and roadworthy. If the TPMS warning light is on because of a safety problem with a wheel or tyre, the vehicle will be unroadworthy and illegal to drive.