TPMS (Tyre Pressure Monitoring Systems)
The purpose of the tyre pressure monitoring system (TPMS) in your vehicle is to warn you that at least one or more tyres are significantly under-inflated, possibly creating unsafe driving conditions. The TPMS low tyre pressure indicator is a yellow symbol that illuminates on the dashboard instrument panel in the shape of a tyre cross-section (that resembles a horseshoe) with an exclamation point.
Questions and Answers
What does TPMS service mean?
TPMS is an electronic system inside the tyre that monitors the air pressure in your tyres. If your tyres are under- or over-inflated, the TPMS activates a warning light on your dashboard. When the light is steady, it means you need to have your tyre pressure checked.
How does TPMS work?
Direct TPMS uses a sensor mounted in the wheel to measure air pressure in each tyre. When air pressure drops 25% below the manufacturer's recommended level, the sensor transmits that information to your car's computer system and triggers your dashboard indicator light (a yellow symbol in the shape of a tyre cross-section that resembles a horseshoe with an exclamation point).
Is TPMS required when replacing tyres?
TPMS include sensors that are mounted on the wheels or valve stems, and the tyre pressure sensors can wear out or be damaged by potholes, debris or the weather and need replacing. On many vehicles, the TPMS needs to be electronically reset after changing or replacing tyres.
How do I turn off the TPMS light?
Use Your Vehicle's TPMS Reset Button. Put the key in the ignition and turn it to the "on" position, but do not start the car. Press and hold down the reset button (sometimes located under the steering wheel) until the low-pressure light blinks three times. Release the button. Alternatively, consult your car’s owner's manual for guidance (hopefully in the glove box).
Can I drive with my TPMS light on?
If the tyre pressure is too low, it can cause unsafe driving conditions. If the TPMS light comes on while you are driving, find the nearest petrol station and check the pressure of the tyres. Driving too long on underinflated tyres can cause tyres undue wear, reduce fuel mileage, and present safety hazards.
Why is my tyre pressure light on when my tyres are fine?
Usually, the car tyre pressure decreases during the cold weather, even when it's properly inflated. This is because, in cold, the matter compresses whereas in the heat it expands. As a result, this turns on the low tyre pressure light (even though the tyres are fine) for a while but disappears once the tyres are warmed. However, if it doesn't turn off, measure the pressure of tyres.
How often do TPMS sensor valves need to be replaced?
A sensor valve normally requires replacing after around 5 years or up to 100,000 miles, although this can vary depending on vehicle use. High mileages and frequent low-pressure alerts can reduce this considerably and given the position of the sensor valves in the wheel, they are also vulnerable to damage and corrosion which means they may be required to be replaced sooner.
How does the car 'recognise' a TPMS new sensor valve?
The car's ECU stores the unique identity number of each valve. When a valve is replaced, the new identity number has to be programmed into the ECU, however, on some models the car "self-learns" simply by being driven.