Novomatic AL21

Novomatic error code AL21 indicates: Novomatic GS / GSU Integrated & Freestanding Electronic Dishwasher Series: Diagnostic fault code AL21 registered by the microcomputer controller. Water supply tap closed or incoming domestic line water pressure below 0.3 bar.

The primary root cause for Novomatic code AL21 is: On Novomatic Austrian and Central European retail OEM chassis appliances engineered with Austrian retail OEM wash system with 1800W flow tube element (27-31 Ω), wash motor (95-125 Ω), and pressure membrane switch: valve inlet tap turned off during plumbing maintenance, or main supply pressure drop. Metrological tolerance verification: water flow delivery rate minimum 10 L/min when bucket test executed at tap; static pressure > 1.0 bar..

To resolve error code AL21: Disconnect mains power before servicing. Unplug the harness at the main PCB and use a calibrated digital multimeter: unscrew supply hose from tap, perform 10-liter bucket flow test in 1 minute, open tap completely and reinstall hose. Inspect contacts for pin oxidation or loose terminals. Replace defective part if out of tolerance, re-energize and clear error: press and hold the Program selector and Start buttons together for 5 seconds until the display beeps and drain pump evacuates remaining water.

Resetting power (unplugging for 5–10 minutes) clears temporary memory errors. However, if Novomatic code AL21 persists, the physical component causing On Novomatic Austrian and Central European retail OEM chassis appliances engineered with Austrian retail OEM wash system with 1800W flow tube element (27-31 Ω), wash motor (95-125 Ω), and pressure membrane switch: valve inlet tap turned off during plumbing maintenance, or main supply pressure drop. Metrological tolerance verification: water flow delivery rate minimum 10 L/min when bucket test executed at tap; static pressure > 1.0 bar. must be inspected or replaced.

Set a digital multimeter to ohms (Ω). Disconnect power and test Mechanical Pressure Switch Contacts / Inductive Frequency Sensor across Across switch spade contacts with harness unplugged; electronic output: 40Hz–50Hz frequency signal. Expected nominal reading is Mechanical: Continuity 0.0Ω–0.2Ω (Empty: 11-12, Full: 11-14). Electronic: 20Ω–45Ω coil resistance.. Tolerance: Mechanical switch contacts must transition cleanly on gentle breath pressure. Coil ~22Ω ±5%..

Standard electrical safety protocol: 1. Disconnect 230V mains power before opening panels. 2. Verify zero voltage at test points. 3. Allow hot water or heating elements to cool below 30°C before handling.