E12 displayed and time-of-day clock resets or loses settings frequently

Safety: Turn off power before opening the control housing.

• Check power source: Ensure the outlet is not controlled by a wall switch and that there are no frequent outages. Use a surge protector if necessary.
• Inspect power plug and cable: Look for damage, loose connections, or corrosion at the plug and socket.
• Open control head: Remove the cover and locate the backup battery or supercapacitor (if used). Check for leakage or swelling.
• Replace backup component: If the battery or capacitor is user-replaceable, install a new one with the same specifications, observing polarity.
• Reprogram settings: After replacement, set the correct time, date, and hardness. Monitor for further resets. Persistent E12 indicates a failing PCB that may need replacement.