Error code reference
Merloni Oven Error Code ER21
Power supply board NTC readings illogical (NTC on main board not reading correctly).
Power supply board NTC readings illogical (NTC on main board not reading correctly).
First step from the service manual
Replace the power supply board.
The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.
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- Step-by-step tests with expected resistance, voltage, and continuity values
- Wiring diagram references and connector pinouts from the OEM service manual
- Verified part numbers when replacement is required
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