E16
SunHeater Relay / Output Driver Fault

Heater shows E16 and will not start; may be accompanied by internal clicking

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Stuck relay on control board, Shorted load (blower, pump relay), Burned PCB traces, Overcurrent event

How to Fix / Troubleshooting

Safety: Turn off power at the breaker. Do not bypass relays or fuses.

  • Inspect loads: Disconnect the Combustion Blower Motor and any auxiliary pump relay outputs from the control board. Check each load for shorts to ground with a multimeter.
  • Visual board inspection: Remove the main control board and inspect the back for burned spots, cracked solder joints, or melted relay cases.
  • Check fuses: Test any onboard fuses and replace only with identical ratings if blown. A repeatedly blowing fuse indicates a shorted load or board.
  • Isolate the fault: Reconnect one load at a time and power up to see if E16 returns. If the error appears only when a specific device is connected, that device is likely faulty.
  • Replace control board if needed: If all loads test good but E16 persists, replace the Main Control Board.
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Repair Difficulty

Professional Required 5/5

Required Part

Main Control Board
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