Smeg oven shows Er12 and the clock/timer cannot be set or loses time.

Safety first: Turn off power at the mains before removing the control panel.

• Power reset: Disconnect the oven from power for 10–15 minutes, then restore power and attempt to set the clock again. Sometimes this clears minor glitches.
• Check supply voltage: Ensure the oven is connected to a stable mains supply. Loose terminal block connections can cause intermittent power to the clock.
• Inspect clock module: Remove the front control panel to access the clock/timer PCB. Look for burnt components or corrosion. Reseat connectors.
• Replace clock module: If the module will not hold time or Er12 persists, replace the clock/timer assembly with the correct Smeg part. Some models integrate the clock into the main control board; in that case, the entire board must be replaced.