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Rinnai · Boiler

999 PC Board / software mismatch

High severity I-Series Plus 150K and smallerI-Series Plus 175K and higher

What the control is telling you

The PC Board and the internal logic do not match.

Applies to: I-Series Plus boilers — 150K BTU and smaller and 175K BTU and higher (Combi and Solo)

Likely causes

  • Harnesses connected to the wrong terminals
  • Wet or corroded board connections
  • Software version mismatch between PC Board and operation board
  • Failed PC Board

Test and repair steps

  1. Confirm every wiring harness is plugged into the correct terminal.
  2. Inspect PC Board connections for moisture or corrosion.
  3. Check that PC Board and operation board software versions match; replace whichever component doesn't match.
  4. Replace the PC Board if the fault remains.
  5. Before swapping the PC Board, write down all parameter settings, then copy them from the old board using the data transfer cable supplied with the new board (see the part's instructions).
  6. If data transfer fails, re-program all parameters and set gas valve values per the Installation and Operation Manual (150K and smaller: also see docs 800000253 and 800000254).

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Source: Rinnai Troubleshooting I-Series Plus Boiler Diagnostic Codes (800000375), p.45. Summarized in our own words; check the original manual for your model.

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For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.