This system tells you your tyre pressure, via your instrument panel, before you set off, and during every journey. Sensors in each wheel (including the spare wheel) and the wheel electronics send radio signals to a control unit with information about tyre pressure and temperature. As each unit has its own code you can easily tell which wheel is affected. If tyre pressure is too low, or there's a sudden loss of pressure, you are warned by visual and/or sound signals. This constant monitoring offers you a high level of safety.
Although the system is a great help, it is still the driver's responsibility to make sure the correct tyre pressure is maintained.
Article source: www.volkswagen.co.uk