Vaillant 0020059717 Sensor (water pressure)

The Vaillant 0020059717 is a water pressure sensor for Vaillant heating appliances. It reads the pressure of the water in the system and passes that signal to the appliance's control board, which uses it to regulate operation and to raise a fault when the reading falls outside the expected range. The sensor is supplied as a single unit and forms part of the boiler's sensors and switches group.

• The pressure reading on the gauge or display is wrong, or moves when the system pressure has not changed
• The appliance locks out or displays a pressure-related fault code
• The boiler fails to fire, or cuts out shortly after ignition
• The displayed pressure stays fixed no matter what happens at the filling loop
• Intermittent faults that clear after a reset and then return

• Match the appliance model and serial number against the part number to confirm the correct sensor
• Note the GC number from the data badge where one is shown, and check it against the appliance records
• Inspect the sealing washer or O-ring at the sensor connection and renew it if it is worn or flattened
• Any work inside the appliance casing should be carried out by a competent person