Tyre Pressure Monitor Sensor Replacement made easy

What is a TPMS sensor?

A TPMS sensor is part of the Tyre Pressure Monitoring System, which warns you when there is a problem with your tyre pressures.
Cars with a direct TPMS have small electronic sensors fitted to the wheels. These measure the pressure inside each tyre and transmit the information to the vehicle.

Not every TPMS works this way. Some cars use an indirect TPMS, which uses information from the ABS wheel-speed sensors to detect when a tyre may be underinflated. These systems do not have a separate pressure sensor inside each tyre.

A TPMS sensor replacement therefore generally applies to vehicles fitted with a direct system.

How much does TPMS sensor replacement cost?

Replacing a single TPMS sensor can cost around £60 to £150, depending on the vehicle, the type of sensor fitted and whether programming or a TPMS relearn procedure is required.

The total cost can also vary depending on whether only one sensor needs replacing or several have failed at a similar time. Sensors on some vehicles are more expensive than others, particularly if an original manufacturer part is required.

A TPMS warning can also be caused by low tyre pressure, a leaking valve or a problem elsewhere in the system.

Where is the tyre pressure sensor located?

On a direct TPMS system, the tyre pressure sensor is located inside the wheel, usually attached to or incorporated into the tyre valve.
Because the sensor sits inside the tyre, the tyre normally needs to be deflated and moved away from the rim before the sensor can be accessed.

You usually cannot identify the condition of the electronic sensor simply by looking at the valve from outside the wheel. A mechanic uses TPMS diagnostic equipment to check whether each sensor is transmitting correctly.

Signs That Your TPMS Sensor Requires Replacement

A faulty TPMS sensor can cause several symptoms, including:

• The TPMS warning light flashing before staying illuminated.
• A tyre pressure reading disappearing from the dashboard.
• One wheel showing no pressure reading while the others work normally.
• Intermittent TPMS warnings even when tyre pressures are correct.
• A sensor failing to respond when checked with TPMS diagnostic equipment.
• Visible corrosion or damage around the TPMS valve.

A warning light does not automatically mean the sensor needs replacing. A solid TPMS warning can sometimes just mean that one or more tyres are underinflated.

If the warning remains after checking and correcting all tyre pressures, the TPMS system should be inspected to identify whether a sensor or another component has failed. The DVSA also distinguishes between a low-pressure warning and an actual system malfunction when assessing TPMS during an MOT.

How long do TPMS sensors last?

TPMS sensors commonly last around 5 to 10 years, although their lifespan varies depending on the sensor and how the vehicle is used.

Direct TPMS sensors contain a small battery which powers the pressure measurement and radio transmitter. The battery is normally sealed inside the sensor and is not designed to be replaced separately.

Once the battery runs out, the sensor will generally need to be replaced. Sensors can also fail earlier because of corrosion, physical damage or damage to the valve components.

What does a TPMS sensor replacement involve?

• The mechanic will first check the TPMS system to determine which sensor is faulty and confirm that the problem is not simply low tyre pressure or a leaking valve.
• The wheel is then removed and the tyre deflated so the faulty sensor can be accessed. The tyre bead may need to be moved away from the wheel rim before the sensor and valve assembly can be removed.
• A suitable replacement sensor is then fitted. Depending on the sensor and vehicle, the mechanic may also need to:
• Program the replacement sensor for the correct vehicle.
• Carry out a TPMS relearn procedure so the car recognises the new sensor.
• Replace valve seals, nuts, cores or other service components.
• Inflate the tyre to the correct pressure.
• Check that the new sensor is communicating correctly and that the TPMS warning has cleared.

The exact process can vary between vehicle models and TPMS systems.

What’s the difference between TPMS sensor vs TPMS valve?

The TPMS sensor is the electronic component that measures tyre pressure and sends the information to the vehicle.

The TPMS valve is the valve through which the tyre is inflated. On many direct TPMS systems, the sensor is attached to the valve inside the wheel, which is why the complete assembly is sometimes referred to as a TPMS “valve” or sensor valve.

They do not always need to be replaced together. For example, corrosion or a leaking valve may sometimes be repaired by replacing the valve stem or service components while keeping the original electronic sensor. If the sensor electronics or internal battery have failed, the sensor itself normally needs replacing.

Does a new TPMS sensor need programming?

In many cases, yes, although programming a sensor and relearning the sensor to the vehicle are two different things.
Some aftermarket TPMS sensors are supplied blank and must first be programmed with the correct vehicle protocol. Other sensors are supplied pre-programmed for a particular vehicle or range of vehicles.

The vehicle may then need to learn the new sensor's unique ID so it knows which sensors are fitted. Depending on the car, this can happen automatically after driving, through a vehicle-specific relearn procedure or using diagnostic equipment.

The mechanic fitting the sensor should make sure it is correctly configured and communicating with the vehicle before completing the job.

Can a faulty TPMS cause an MOT failure?

Yes. For M1 passenger vehicles first used on or after 1 January 2012, a TPMS that is malfunctioning or obviously not working is classed as a major defect, which means the vehicle will fail its MOT.

However, a TPMS warning light does not automatically mean there is a system fault.

If the warning is simply showing that a tyre is underinflated, this is treated differently from a malfunctioning TPMS. The MOT tester will assess whether the warning appears to indicate low pressure or a fault with the monitoring system itself.

If your TPMS light remains on after all four tyres have been inflated correctly, it is worth having the system checked and fixed before your MOT.