Ariston Washer Error Code F04

F04 on an Ariston washer means the control board is detecting a contradictory condition from the pressure sensor: it is registering both an overflow signal and an empty-drum signal at the same time. This indicates the pressure sensor is stuck reading empty, which is not a normal operating state. The machine halts operation as a safety measure until the fault is diagnosed and corrected.

No, you should not continue running the washer while the F04 error is active. Because the pressure sensor is not accurately reporting the water level, the machine cannot reliably control how much water enters the drum. This creates a risk of overfilling or improper drainage behavior. Stop use until the fault is diagnosed and resolved.

A power reset may temporarily clear the F04 fault code, but it will almost certainly return if the underlying problem with the pressure sensor, its hose, or the wiring connections has not been fixed. Resetting the machine without addressing the root cause is not a lasting solution. Perform a proper diagnostic starting with the CN1 Connector Card terminals before attempting to put the machine back into regular service.

Some causes of F04 are DIY-friendly, such as checking the CN1 Connector Card terminals for corrosion or looseness and inspecting the pressure sensor hose for kinks or blockages. Clearing a clogged pressure hose or reseating a connector requires no special tools. However, testing and replacing the pressure sensor or control board typically requires electrical testing experience and is better handled by a qualified technician.

Repair costs vary depending on the root cause. If the fix involves only cleaning the pressure hose or reseating a connector, costs may be minimal or limited to a service call fee, typically in the range of $75 to $150. Replacing the pressure sensor usually adds $30 to $80 in parts. A control board replacement is the most expensive scenario, with parts and labor potentially ranging from $200 to $400 or more depending on the model.