Heater shows F17; unit may overheat quickly or report unrealistic temperature changes.

Safety first: Turn off power and allow the heater to cool.

• Locate outlet sensor: Identify the Nirvana outlet water temperature sensor on the water manifold (often near the outlet union).
• Inspect installation: Ensure the sensor is fully seated in its well or threaded port and making good thermal contact.
• Check wiring: Verify that inlet and outlet sensor connectors are not swapped on the control board. Inspect for damaged insulation or loose pins.
• Resistance test: Measure sensor resistance and compare to the Nirvana chart. Replace if out of spec.
• Re-test: After replacement, restore power and monitor temperature readings for stability.