Control displays 'Internal Error', 'Control Fault', or random/unstable codes; unit may behave unpredictably.

Safety first: Turn off power. Do not touch control circuitry with wet hands.

• Power cycle: Turn off power for at least 30 seconds, then restore. Observe whether the fault clears or returns immediately.
• Inspect control enclosure: Remove the control cover and look for signs of moisture, corrosion, or burned components. Address any water leaks above the control before replacing parts.
• Check all harnesses: Reseat all plug-in connectors to the control board to ensure good contact.
• Verify proper grounding and power: Confirm that line voltage and neutral are correctly connected and that ground is secure. Incorrect wiring can damage controls.
• Replace control if necessary: If internal fault indications persist and wiring/power are correct, the control module should be replaced with the exact Weil-McLain part number.