Zerowatt SpazioTop / LadyPiù / Optima Washing Machine: Electronic pressure sensor calibration fault E20; signal frequency received from the analog pressure transducer is out of valid bounds.
On Zerowatt washing machines powered by integrated GIAS Invensys circuit architecture, electronic commutator drive motor, and mechanical pressure calibration: Blocked pressure tube, punctured silicone diaphragm, or defective oscillator in electronic pressure switch (~25.6 kHz empty).
Inspect rubber pressure hose for pinholes or splits. Blow through tube towards tub to clear compression dome. Measure sensor output frequency (~25.6 kHz empty). Turn dial to Off, hold Start/Pause and Spin speed buttons together for 5 seconds until the status lamps pulse, then power cycle.
