Utica Dunkirk E109

What does Utica Dunkirk E109 mean?

E109 on the Dunkirk DCC/DCB/DCCF condensing boiler is a temporary pre-circulation alarm. The boiler runs the circulator pump before ignition to verify water flow is present. If the control does not detect adequate flow during this pre-circulation check, it logs E109 and delays or halts the ignition attempt. This is a soft lockout that prompts inspection of the circulation and sensor wiring.

Symptoms

• E109 displayed on the boiler panel during the start-up sequence before ignition.
• Pump runs during pre-circulation but the boiler does not advance to ignition.
• No heating or hot water output.
• Code may clear and recur cyclically if the flow condition is intermittent.

Common causes

• Circulator pump not running or delivering insufficient flow during the pre-circulation phase.
• Supply and return NTC sensor wiring swapped — control cannot detect a valid temperature differential.
• Air trapped in the primary circuit blocking flow through the heat exchanger.
• NTC temperature sensor loose or disconnected from its pipe fitting.

Diagnostic steps

1. 01

   Verify pump operation

   With a heat demand active, confirm the circulator pump is running by listening and feeling for vibration. If silent, check pump wiring connections and verify 120V at the pump terminals.

2. 02

   Check supply and return sensor wiring polarity

   Confirm the supply NTC sensor is connected to the supply pipe fitting and the return NTC is on the return pipe — they must not be swapped. Swapped sensors produce a flat or inverted temperature differential.

3. 03

   Purge air from the system

   Bleed air from all high points and radiators. Confirm system pressure is at 15–20 psi before restarting. An air-locked circuit will not show a temperature rise during pre-circulation.

4. 04

   Inspect NTC sensor connections

   Check that both NTC sensors are fully inserted into their pipe pockets and that their wiring plugs are securely connected to the control board harness.

5. 05

   Reset and test

   After correcting any pump or sensor issues, reset the boiler and observe whether it advances past the pre-circulation phase to ignition without displaying E109.

When to call a professional

Call a licensed technician if E109 persists after verifying pump operation, sensor wiring, and system air purging, or if the circulator pump requires replacement. Persistent pre-circulation failures that cannot be resolved with basic checks indicate a control board fault or complex system flow issue requiring professional diagnosis.