Unit displays E6 and will not heat; may occur after a power surge or lightning event.

Safety: Turn OFF power at the breaker before opening the unit.

• Power reset: Turn the breaker OFF for at least 5 minutes to fully discharge internal capacitors, then turn it back ON. Sometimes this clears transient internal faults.
• Inspect the control board: Remove the front cover and visually inspect the main control board for burn marks, bulging capacitors, or signs of water intrusion.
• Check low-voltage connections: Ensure all small signal connectors (sensors, display, flow sensor) are firmly seated. A loose harness can trigger communication errors.
• Environment check: Verify the unit is not installed in a location with excessive condensation or dripping water that could damage electronics.
• Next steps: If E6 persists after a power reset and connector check, the control board is likely defective. Replacement typically requires transferring all wiring one terminal at a time to the new board.
• Recommendation: Due to the risk of miswiring and shock, control board replacement is best handled by an experienced technician or electrician.