Display shows 'Err' or 'Error' and the cooker refuses to start any program.

Safety first: Disconnect the appliance from mains before any disassembly.

• Factory reset (if available): Consult your specific Oursson model manual for a reset procedure (often holding certain buttons while plugging in). Perform the reset to clear stored faults.
• Power reset: Unplug the cooker for at least 30 minutes to allow capacitors to discharge and the microcontroller to fully reset. Then reconnect and test.
• Check environment: Ensure the cooker is in a dry, room-temperature environment. Extreme cold or heat can cause sensor readings to go out of range.
• Test basic functions: Try a low-temperature program (e.g., keep warm) with the inner pot installed. If 'Err' appears immediately, a core sensor or board fault is likely.
• Service requirement: Generic 'Err' codes usually indicate a failure that cannot be resolved without diagnostic tools. Contact an authorized Oursson service center for board-level diagnostics.