Code 55: Control board memory indicates multiple previous faults; intermittent operation.

Safety first: Turn off power before tightening any wiring connections.

• Step 1 – Review recent symptoms: Note any recent no-heat events, short cycling, or unusual noises to correlate with stored faults.
• Step 2 – Inspect wiring: Gently tug on low-voltage and high-voltage connections at the board, gas valve, pressure switch, and limits. Tighten any loose spade or screw terminals.
• Step 3 – Clear history (if allowed): Some Ducane boards allow clearing fault history by power cycling or specific button sequences. After clearing, monitor for new codes.
• Step 4 – Address root causes: Use current active codes and symptoms to guide further troubleshooting rather than relying solely on history.