F0
Peerless Weak or Unstable Flame Signal

Boiler shows F0 fault and locks out; may be labeled 'Flame Signal Error'

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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

Dirty flame rod, poor burner ground, low gas pressure, incorrect combustion settings

How to Fix / Troubleshooting

Safety first: Turn off power and gas before opening the burner compartment.

Steps:

  • Clean flame rod: Remove the flame sensor rod from the burner assembly. Gently clean with fine emery cloth until shiny. Do not sand excessively.
  • Check grounding: Ensure the burner assembly and control board ground connections are tight and free of rust.
  • Inspect burner: Clean burner ports and ensure even flame distribution.
  • Restore gas and power: Reset the boiler and observe operation. If the flame signal remains weak, a technician should check gas pressure and adjust combustion using a combustion analyzer.
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Repair Difficulty

Hard 4/5

Required Part

Flame sensor
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