Heater shows E05 and will not start a heating cycle.

Critical safety warning: A rollout fault indicates a potential combustion hazard. Turn off power and gas immediately. Do not continue to operate the heater until the cause is found.

• Inspect rollout switches: Locate the rollout switches near the burner compartment. Check for manual reset buttons; if present, press to reset once only after the unit has cooled. If they trip again, stop and call a professional.
• Check for visible obstructions: Look for debris, nests, or soot buildup in the burner area and exhaust outlet. Do not operate the heater with any visible blockage.
• Examine burners (visual only): If burners appear heavily rusted, warped, or sooted, they may be causing improper flame. Burner removal and cleaning should be done by a qualified technician.
• Professional inspection: Because rollout can indicate a cracked heat exchanger or serious venting problem, have a licensed pool heater technician inspect the combustion chamber, heat exchanger, and venting system before returning the heater to service.