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Navien Boiler Error Codes: Meanings & Safe Checks
Choose the code exactly as shown. Meanings and reset procedures can change across model families, display formats and markets.
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E001 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E001 as heat exchanger overheat. Search/display variants: E001 stop-use E003 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E003 as ignition failure. Search/display variants: E003 stop-use E004 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E004 as false flame. Search/display variants: E004 stop-use E012 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E012 as flame loss. Search/display variants: E012 stop-use E016 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E016 as heat exchanger overheat. Search/display variants: E016 stop-use E030 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E030 as exhaust overheat. Search/display variants: E030 stop-use E031 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E031 as burner overheat. Search/display variants: E031 stop-use E046 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E046 as heat exchanger thermistor error. Search/display variants: E046 caution E047 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E047 as exhaust thermistor error. Search/display variants: E047 caution E060 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E060 as abnormal dual venturi. Search/display variants: E060 caution E109 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E109 as abnormal fan motor. Search/display variants: E109 caution E110 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E110 as exhaust blockage. Search/display variants: E110 stop-use E205 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E205 as heating supply temperature sensor error. Search/display variants: E205 caution E218 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E218 as heating return temperature sensor error. Search/display variants: E218 caution E278 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E278 as external supply sensor not detected. Search/display variants: E278 caution E279 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E279 as external return sensor not detected. Search/display variants: E279 caution E291 The official NFB-H Condensing Boilers Installation Manual identifies E291 as heating return temperature exceeds the heating supply temperature. Search/display variants: E291 caution E302 The official NFB-H Condensing Boilers Installation Manual identifies E302 as low water pressure. Search/display variants: E302 caution E351 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E351 as abnormal automatic feeder valve. Search/display variants: E351 caution E352 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E352 as high water pressure. Search/display variants: E352 caution E353 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E353 as water pressure sensor error. Search/display variants: E353 caution E407 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E407 as domestic hot-water outlet sensor error. Search/display variants: E407 caution E421 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E421 as domestic cold-water inlet sensor error. Search/display variants: E421 caution E434 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E434 as abnormal water-adjustment valve. Search/display variants: E434 caution E439 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E439 as no domestic water flow detected. Search/display variants: E439 caution E441 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E441 as domestic hot-water outlet sensor 2 error. Search/display variants: E441 caution E445 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E445 as abnormal mixing valve. Search/display variants: E445 caution E480 The official NFB-H Condensing Boilers Installation Manual identifies E480 as domestic hot-water tank sensor not detected. Search/display variants: E480 caution E515 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E515 as abnormal pcb. Search/display variants: E515 caution E517 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E517 as abnormal dip switch. Search/display variants: E517 caution E594 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E594 as abnormal eeprom. Search/display variants: E594 caution E615 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E615 as abnormal memory. Search/display variants: E615 caution E736 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E736 as cascade communication error. Search/display variants: E736 caution E740 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E740 as outdoor sensor not detected. Search/display variants: E740 caution E761 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E761 as pump aquastat not detected. Search/display variants: E761 caution E762 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E762 as vent pipe not fully inserted. Search/display variants: E762 stop-use E773 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E773 as improper gas type detected. Search/display variants: E773 stop-use E777 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E777 as low-water cutoff activated. Search/display variants: E777 stop-use E782 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E782 as front-panel communication error. Search/display variants: E782 caution E784 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E784 as zone-controller communication error. Search/display variants: E784 caution E786 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E786 as improper front panel. Search/display variants: E786 caution E788 The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E788 as incorrect gas-type setting. Search/display variants: E788 stop-use