E9
Ruud
Internal Control Error / Configuration Fault
Boiler shows E9 and will not operate; may occur after a power event or wiring work
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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
Incorrect dip‑switch or parameter settings, corrupted control firmware, incompatible replacement control board, wiring error on low‑voltage terminals
How to Fix / Troubleshooting
Safety first: Turn off power before touching the control board or wiring.
- Check dip‑switches/jumpers: Compare the control board dip‑switch or jumper positions to the Ruud installation manual for your exact boiler model. Incorrect settings can trigger E9.
- Inspect low‑voltage wiring: Verify thermostat, outdoor sensor, and pump relay wiring are on the correct terminals and not shorted.
- Factory reset (if supported): Some Ruud controls allow a parameter reset to factory defaults. Follow the manual exactly; incorrect resets can disable features.
- If E9 persists: The control board may be damaged or incorrectly specified for the boiler. Replacement and reconfiguration should be done by a Ruud‑qualified technician.
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Repair Difficulty
Professional Required
5/5
Required Part
Main Control Board (Ruud Boiler PCB)
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