E08
Slant/Fin Internal Control Board Fault

Boiler display shows E08, system will not fire, may occur after power surge

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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

Damaged boiler control board, Power surge or incorrect polarity, Loose control harness connections, Shorted low-voltage circuit on Slant/Fin boiler

How to Fix / Troubleshooting

Safety: Turn off power at the breaker and verify with a non-contact tester before touching internal wiring.

Steps:

  • 1. Power cycle: Turn off power for at least 2 minutes, then restore. If E08 reappears immediately, continue below.
  • 2. Inspect wiring harnesses: Remove the front panel and visually inspect all plug-in connectors on the control board. Reseat each connector firmly.
  • 3. Check for shorts: Look for any low-voltage thermostat or sensor wires pinched against sharp metal edges or touching high-voltage components.
  • 4. Verify line polarity and ground: Ensure hot, neutral, and ground are correctly wired at the boiler junction box. Incorrect polarity can damage electronics.

Professional repair: If E08 persists, the control board is likely defective and must be replaced with the correct Slant/Fin OEM control. This should be done by a technician to ensure proper setup and safety checks.

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Repair Difficulty

Professional Required 5/5

Required Part

Boiler Control Board
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