Utica Dunkirk E06 Error Code
Return temperature sensor short circuited Bad connection Sensor fault Sensor not
Source: dmg-240__utdu-dmg-240-iom.pdf
What does Utica Dunkirk E06 mean?
E06 on the Utica-Dunkirk DMG-240 condensing boiler indicates the return water temperature sensor has a short circuit — the sensor reads near-zero resistance, which the control board interprets as an impossibly high return temperature. The boiler locks out because it cannot safely monitor the return circuit without a valid sensor reading, which is essential to differential temperature and circulation control logic.
Symptoms
- Boiler display shows E06 on startup or mid-cycle
- Return temperature reading on the display is erroneously high or missing
- Boiler locks out and cannot be cleared by reset alone
- Fault is persistent if the sensor is truly shorted
Common causes
- Return NTC sensor internal short circuit (sensor failure)
- Return sensor harness shorted — conductors pinched together or grounded
- Moisture or condensate ingress at the return sensor connector
- Sensor body grounding to metallic pipe fitting
Ask the AskWhiz AI about Utica Dunkirk E06
AskWhiz
online
Diagnostic steps
Disconnect and test return sensor resistance
Disconnect the return NTC sensor connector and measure resistance across the sensor terminals. A near-zero or very low reading at ambient temperature confirms the sensor is shorted.
Inspect the wiring harness for damage
Trace the return sensor harness from the sensor to the PCB and look for pinched sections, abraded insulation, or corroded connectors that could cause a short.
Check the sensor connector for moisture
Dry and clean the sensor connector and PCB header. Condensate near the heat exchanger is common and causes conductive shorts at connectors.
Replace the return NTC sensor
Install an OEM replacement return NTC sensor, seat it fully in the return pipe pocket, and reconnect the harness. Confirm resistance at ambient temperature matches the NTC curve.
Reset and confirm operation
Press RESET for 2 seconds and verify the return temperature reading rises appropriately during a heating cycle. E06 should clear after a valid sensor is installed.
When to call a professional
If E06 returns after sensor replacement, the PCB return sensor input circuit is shorted and requires PCB replacement. PCB replacement must be performed by a qualified technician and followed by the full automatic and manual calibration commissioning sequence. Do not continue resetting without addressing the root cause, as uncorrected sensor faults can mask real overheat conditions.
Stop searching through PDFs. Our AI assistant on WhatsApp is trained on official Utica Dunkirk documentation and can diagnose this fault code and guide you through the repair in minutes.
Free tier — 10 messages/month, no credit card.
Other Utica Dunkirk Error Codes
,E28,E40,E50,E160,E321,and E431 -Indicate possible faulty components. 53 - Indic
, 78 and 92 - Indicates possible wrong calibration, a new calibration is needed.
,E135 - Indicate the gas supply has been interrupted, ignition has failed or fla
,E 133, E 134,E 135, E 09,E 15,E 128 and E 384 - are displayed it is possible to
Gas Valve Connection Cable 日 10 External Probe Fault 12 Water Flow Switch Open 1
Water Refill Enabled E 19 Max Time Of Water Refill 20 Central Heating Flow NTC F
Flue NTC Fault E40 Central Heating Return NTC Fault Hot Water NTC Fault (tank ve
PCB to be set by the "Calibration Function" E 171 Fan parameter Out of range in
87 Communication error E92 Combustion test alarm during auto-setting E 1 109 Pre
E11 between the supply and return temperatures too Sensor not/poorly connected N
Temperature of heat exchanger is above the normal range (high- limit thermostat
5 burner start-up failures that the air inlet and exhaust flue are not blocked C
Sources: dunkirk.com