Topside control panel displays “dy” and spa shuts down heating; may follow a “dr” code.

Safety first: Turn off power at the GFCI breaker before working on the spa.

• Verify water level and flow: Confirm spa is properly filled. Remove and clean the filter cartridge. Try running the spa briefly with the filter removed to see if flow improves.
• Bleed air from heater: Open the equipment compartment. Locate the heater manifold. Loosen the union on the heater inlet slightly until water flows steadily, then retighten.
• Power cycle: Turn the breaker off for 30–60 seconds, then back on. Observe if the circulation pump runs and if the “dy” code clears.
• Check for heater overheating: Carefully feel the outside of the heater tube (only when power is off). If it shows signs of scorching or melted insulation, the heater may have dry-fired and must be replaced.
• If error returns quickly: The heater relay on the IQ control board may be sticking closed or not energizing correctly. This is an advanced electrical repair and should be handled by a spa technician.