E17
Pennco Communication Fault (Control to User Interface or Add-on Module)

Boiler shows E17 and may not respond to thermostat

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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

Loose communication cable, Damaged low-voltage harness, Incorrectly wired add-on control (e.g., zone panel), Faulty display or main control board

How to Fix / Troubleshooting

Safety first: Turn off power before unplugging or plugging any control cables.

  • Inspect communication cable: Locate the cable between the main control board and any remote display or add-on module. Ensure connectors are fully seated.
  • Check for damage: Look for pinched or cut low-voltage wires, especially where they pass through cabinet openings.
  • Isolate add-ons: Temporarily disconnect non-essential modules (e.g., external zone controllers) and see if the boiler operates normally.
  • Reset control: Power cycle the boiler and observe if E17 clears.
  • If fault persists: Either the display module or the main control board may need replacement, which should be done by a technician.
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Repair Difficulty

Hard 4/5

Required Part

User Interface / Display Module
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