Utica Dunkirk E20

What does Utica Dunkirk E20 mean?

E20 indicates a fault with the Central Heating (CH) flow NTC temperature sensor on Utica-Dunkirk DCC/DCB condensing boilers. The control board cannot read a valid signal from the sensor, so the boiler locks out to prevent uncontrolled heating. The sensor measures supply-side water temperature and is critical to modulation and safety control.

Symptoms

• Boiler display shows E20 and burner shuts down
• No central heating output despite heat demand
• Boiler enters lockout and will not restart automatically
• Control panel fault indicator illuminates

Common causes

• Faulty or failed CH flow NTC temperature sensor
• Loose or corroded wiring connector at the sensor or PCB
• Broken or shorted sensor lead wire
• PCB input circuit failure

Diagnostic steps

1. 01

   Check wiring and connectors

   Inspect the wiring harness between the CH flow NTC sensor and the PCB. Look for loose pins, corrosion, or damaged insulation and reseat any loose connectors.

2. 02

   Measure sensor resistance

   Disconnect the sensor and use a multimeter to measure resistance. Cross-reference the reading against the NTC resistance-temperature chart in the IOM; an open circuit or significantly out-of-range value confirms sensor failure.

3. 03

   Replace the CH flow NTC sensor

   Install a replacement OEM NTC sensor, verify it is seated correctly in the sensor pocket, and reconnect the wiring harness securely.

4. 04

   Reset the boiler

   Press and hold the RESET button for at least 2 seconds. If E20 clears, confirm normal operation through a full heating cycle.

5. 05

   Contact technical service if fault persists

   If E20 returns after sensor replacement, the PCB input channel may be defective. Contact Utica-Dunkirk technical service at 1-800-325-5479.

When to call a professional

Call a licensed HVAC technician if the fault persists after inspecting wiring and replacing the sensor, or if you are not equipped to perform electrical continuity and resistance measurements safely. PCB replacement requires a qualified technician to configure and calibrate the control board per the manufacturer's commissioning procedure to avoid introducing additional faults.