Heater shuts down with E03; fan or blower may continue briefly then stop

Safety first: Turn OFF power and gas. Allow the heater to cool completely before touching internal components.

• Inspect exhaust vent: Check the flue outlet and vent piping for obstructions such as leaves, nests, or debris. Ensure vent terminations meet Poolworld clearance requirements and are not blocked by snow or landscaping.
• Check for soot: Remove the front panel and visually inspect the heat exchanger and burner area for black soot or discoloration, which indicates poor combustion. If heavy soot is present, stop and call a professional for cleaning and combustion analysis.
• Verify water flow: Ensure the pool pump is running at the correct speed and that valves to and from the heater are fully open. Clean the pool filter and skimmer baskets to restore proper flow.
• Inspect high limit switch wiring: Locate the flue or water high limit switch on the header or flue collector. Check for loose or corroded connectors. Reseat them firmly.
• Reset and test: After clearing any obstructions and ensuring good water flow, restore power and gas, then call for heat. If E03 recurs, the high limit switch or control board may be faulty and should be tested and replaced if necessary.

Warning: Persistent high-limit trips can indicate dangerous overheating or venting issues. Do not operate the heater until the cause is corrected.