Boiler displays E16; pump may not run or may run continuously

Safety first: Turn off power before touching the pump or electrical connections. Hot water can cause burns.

• Check pump wiring: Verify the circulator is wired to the correct pump terminals on the Ruud control and that connections are tight.
• Inspect pump for overheating: A very hot, non‑running pump may be seized. In this case, replacement is usually required.
• Test pump separately (advanced): A technician can power the pump directly from a known good source to confirm if it runs. If it does, the control relay is likely faulty.
• Replace faulty component: Replace the circulator if it is seized or shorted. If the pump is good but E16 persists, the control board pump relay section may need replacement.