Control panel displays dy or DY, spa stops heating and may shut down temporarily.

Safety first: Shut off power at the GFCI breaker before inspection.

• Allow heater to cool: Wait at least 30 minutes for the heater tube to cool before touching any components.
• Inspect and clean filter: Remove the Aquaterra Spas filter cartridge and clean thoroughly. Replace if the pleats are collapsed or heavily stained.
• Check water flow: With power restored, verify that water is moving strongly from the heater return and through the filter area. Weak or no flow indicates a circulation or jet pump issue.
• Observe for recurring code: If dy appears only when jets are on high speed, the heater may be starved for flow. Ensure all slice valves in the equipment bay are fully open and that no jets are closed off.
• Inspect flow switch and pump: If flow appears normal but dy persists, the flow switch or circulation pump may be malfunctioning and should be tested and replaced if necessary.

Repeated dy errors can permanently damage the heater. If basic cleaning and flow checks do not resolve the issue, schedule professional service.