Indesit Washer Error Code F04

The F04 error code on an Indesit washer indicates that the pressure switch is stuck in the empty position. The pressure switch, also called a water level sensor, is responsible for detecting how much water is inside the drum. It works by responding to air pressure changes transmitted through a small rubber hose connected to the drum. When the machine fills with water, the rising water level compresses air in this hose, which in turn moves a diaphragm inside the pressure switch to signal the control module that the drum has reached the correct fill level. If the switch remains locked in the empty state, the module receives a continuous signal that the drum is empty even when it contains water, causing the machine to halt and display F04.

The most likely causes of this fault include a faulty pressure switch that has failed internally, a blocked or kinked pressure hose preventing air pressure from reaching the switch, or poor electrical connections between the pressure switch and the main control module. Debris or detergent residue can block the small port on the pressure hose fitting at the drum, stopping air pressure transmission entirely. In some cases, the control module itself may be misreading a valid signal from the switch due to a wiring or connector fault.

Diagnosis should begin with a careful inspection of all wiring connectors between the pressure switch and the control module, looking for corrosion, loose pins, or damaged wiring. The pressure hose should be removed and checked for blockages, splits, or kinks along its length. If the hose and connections are found to be sound, the pressure switch itself should be tested or replaced, as the internal diaphragm or contacts may have failed.