11
American Standard Internal Control Board Failure

Error code 11 and furnace does not respond to thermostat, LED indicates internal control fault

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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

Surge damage to integrated furnace control, Corroded board connectors, Repeated short cycling overheating the board, Manufacturing defect in control logic

How to Fix / Troubleshooting

Safety: Turn off power before handling the control board.

Error 11 typically indicates an internal fault in the integrated furnace control.

  • Power cycle:
    • Turn off the furnace switch for 5 minutes, then restore power.
    • If the error returns immediately, the board is likely defective.
  • Inspect wiring harnesses:
    • Unplug and re-seat multi-pin connectors to the board.
    • Look for burnt traces, swollen components, or moisture damage.
  • Replace the control board:
    • Label all wires before removal.
    • Install the exact American Standard replacement board, transferring any jumper settings per the installation instructions.
  • If you are not experienced with furnace controls, have a licensed technician perform the replacement and startup checks.
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Repair Difficulty

Hard 4/5

Required Part

Integrated Furnace Control Board
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