Poolex pool heater displays E2 and will not start heating.

Safety: No special hazards beyond normal electrical safety. Turn off power before accessing sensors.

Steps:

• Check outdoor temperature: Compare with the minimum operating temperature specified in your Poolex manual. If below, the unit may intentionally lock out to protect itself.
• Inspect ambient sensor: Verify that the ambient sensor is correctly positioned and not directly exposed to hot exhaust air or direct sunlight.
• Compare readings: If the Poolex display shows a very different outdoor temperature than reality, the ambient sensor may be faulty and should be replaced.

If E2 appears even in mild weather with a correct sensor, the main control board may need professional diagnosis.