Display shows E20 and pump stops; often associated with internal fan noise or overheating drive

Safety first: Disconnect power before opening the controller enclosure.

• Improve ventilation: Ensure the controller has adequate clearance on all sides and is not enclosed in a sealed box. Provide airflow or ventilation openings.
• Clean vents: Remove dust, debris, and cobwebs from controller vents and heat sink fins.
• Check fan operation: With the cover removed and power restored briefly, observe whether the internal fan starts when the pump runs. Replace the fan if it does not operate.
• Relocate or shade: If the controller is exposed to direct sunlight or high ambient temperatures, provide shading or relocate it to a cooler area.
• Replace controller: If E20 persists despite proper cooling and a working fan, the temperature sensing circuit may be faulty and the controller should be replaced.