Ariston Pressure Sensor Electrical Fault

Error 403, pressure sensor reading inconsistent or out of range.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Loose sensor connector, Damaged sensor wiring, Faulty pressure transducer, Control board fault

Safety: Isolate power before accessing the control compartment.

Locate the pressure sensor: On Ariston units, the sensor is usually mounted on the hydraulic block with a small electrical connector.
Inspect and reseat connector: Unplug the connector, check for corrosion or bent pins, and reconnect firmly.
Check cable routing: Ensure the cable is not pinched or rubbing against sharp edges.
Reset the furnace: Restore power and reset. If 403 returns immediately, the sensor or control board likely needs replacement by a technician.

Medium 3/5

Water Pressure Sensor

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