| 10 | Insufficient water pressure (intervention of the water shortage pressure switch). | The water pressure switch opens due to low pressure or is faulty, causing the PCB to interpret a lack of water. Check the actual pressure with a manometer and the continuity/closure of the pressure switch at its threshold (≈0.5–1.2 bar) and inspect the wiring. |
| F.22 | Installation pressure too low (shutdown due to lack of water). | A faulty or disconnected water pressure sensor/pressure switch can report low pressure and cause a lockout. Check the actual pressure and the sensor's signal/voltage and its wiring harness, comparing with a manometer. |
| F.73 | Error: water pressure sensor not connected or short-circuited (signal too low). | The water sensor/pressure switch does not deliver a valid signal or is shorted, so the electronics do not "see" pressure. Check power supply (≈5 V), wiring continuity, and the sensor's output signal to the PCB. |
| F.74 | Error: electrical problem with the water pressure sensor (signal out of range/high). | Shorts at 5/24 V or internal fault of the sensor/pressure switch cause invalid reading. Check with a multimeter for possible short circuits/voltage in sensor lines and replace if necessary. |
| F.75 | Fault: pressure sensor (defective pressure capsule). | The manometric capsule of the sensor/pressure switch is damaged and delivers an incorrect signal. Compare the sensor reading with the actual pressure, and if it does not vary with pressure changes, replace the component. |
