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Navien Fault Codes
Select a fault code to see its meaning, common causes and how to fix it.
- E003 The E003 code appears on Navien boilers and water heaters when the unit has attempted to light the burner but failed to… Read more →
- E004 The E004 code appears when your Navien boiler detects a flame signal at a point in the firing cycle when the burner… Read more →
- E012 The E012 code appears on Navien boilers when the unit fires up successfully but then loses its flame mid-operation and… Read more →
- E016 The E016 code on a Navien boiler signals that the secondary (plate) heat exchanger has reached an unsafe temperature… Read more →
- E030 The E030 code is a safety lockout triggered when the exhaust gas temperature climbs above approximately 65°C, causing… Read more →
- E046 The E046 code on Navien boilers and hot water heaters is used across different product ranges and can point to one of… Read more →
- E047 The E047 fault code on a Navien boiler signals that the control board has detected an abnormality with the exhaust… Read more →
- E060 The E060 fault code on Navien boilers and water heaters indicates that the unit has detected an abnormality with the… Read more →
- E109 The E109 code on a Navien boiler indicates that the fan motor is not reaching the correct operating speed. Your… Read more →
- E110 The E110 code means the Navien unit's control board has detected that air pressure within the combustion system is… Read more →
- E127 The E127 code on Navien boilers and hot water units indicates a problem with the Air Pressure Sensor (APS) — either an… Read more →
- E205 The E205 code appears when your Navien boiler detects a problem with the heating supply (flow) thermistor — the small… Read more →
- E218 The E218 fault code on a Navien boiler indicates a problem with the heating return thermistor — the temperature sensor… Read more →
- E302 The E302 code appears on Navien boilers when the heating system pressure has dropped below the minimum threshold —… Read more →
- E351 The E351 code appears on Navien combi boilers when the central heating circuit cannot reach or hold its target pressure… Read more →
- E352 The E352 fault code on Navien boilers signals that the system has detected excessively high water pressure.… Read more →
- E353 The E353 code on a Navien boiler signals an abnormal reading from the water pressure sensor. The boiler's control board… Read more →
- E407 The E407 code on a Navien boiler or water heater indicates a problem with the hot water outlet thermistor — the small… Read more →
- E421 The E421 code appears on Navien boilers and water heaters when the appliance detects an open or short circuit in the… Read more →
- E432 The E432 fault code on Navien boilers and water heaters (commonly seen on NPE-series units) signals that the cold water… Read more →
- E434 The E434 fault code on Navien boilers and water heaters (particularly the NPE series) indicates that the unit has… Read more →
- E438 The E438 code appears when the Navien unit detects that its recirculation pump has been switched on but the flow sensor… Read more →
- E439 The E439 fault code on Navien boilers indicates that the system has detected a flow sensor signal error. In practical… Read more →
- E441 The E441 code appears on Navien NPE-series combi boilers and tankless water heaters when the unit detects an open or… Read more →
- E445 The E445 code appears on Navien boilers — most commonly the NPE series — when the control system detects that the… Read more →
- E480 The E480 code appears when your Navien boiler or water heater detects a problem with the external tank thermistor — the… Read more →
- E515 The E515 code on a Navien boiler indicates an internal PCB (Printed Circuit Board) communication failure. In plain… Read more →
- E517 The E517 code appears on Navien boilers when the unit's self-diagnostic system detects that the DIP switch… Read more →
- E593 The E593 code on a Navien boiler signals that the control board has detected an abnormal condition with one or more of… Read more →
- E594 The E594 code on a Navien boiler signals either a partial PCB communication breakdown or an EEPROM fault. Put simply,… Read more →
- E615 The E615 code on a Navien boiler signals an internal electronics fault — specifically, the boiler's control board has… Read more →
- E736 The E736 code appears on Navien water heaters and boilers installed in a cascade arrangement — that is, two or more… Read more →
- E740 The E740 code signals that the boiler has detected an abnormal reading from the outdoor temperature sensor — either an… Read more →
- E760 The E760 code on a Navien tankless water heater (combi or hot water unit) is a scheduled maintenance reminder rather… Read more →
- E782 The E782 fault code on Navien boilers (including the NPE range) indicates an abnormal communication failure between the… Read more →
- E783 The E783 code appears on Navien boilers when the appliance detects a problem with the OpenTherm (OT) remote controller… Read more →
- E785 The E785 code appears on Navien boilers when the control board detects abnormal operation of the flow switch or flow… Read more →
- E787 The E787 code appears on Navien boilers when a manual reset attempt has not completed successfully. Rather than… Read more →