Boiler displays E13 and shuts down during operation

Safety first: Turn off power. Condensate is mildly acidic; wear gloves and eye protection.

• Locate condensate trap: On Utica condensing boilers, find the clear or opaque plastic condensate trap at the bottom of the heat exchanger or flue outlet.
• Remove and clean: Place a shallow pan under the trap, disconnect hoses, and remove the trap. Flush thoroughly with clean water to remove sludge and debris.
• Inspect hoses: Check all condensate hoses for kinks, sags, or blockages. Ensure the line slopes continuously downward to the drain.
• Check drain termination: Verify the drain is not frozen (in cold climates) or blocked at the floor drain or condensate pump.
• Reassemble and test: Reinstall the trap, reconnect hoses securely, restore power, and reset the boiler. Confirm that condensate flows freely during operation.