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Navien NPE-A2 error codes

Every checked code for the Navien NPE-A2 range, with what it means and whether you can fix it yourself.

Error codes

Code Meaning What you can do
E003 Ignition failure Safe checks first, then a pro
E004 False flame detected Safe checks first, then a pro
E012 Flame lost Safe checks first, then a pro
E016 Heat exchanger overheated Safe checks first, then a pro
E030 Exhaust too hot Safe checks first, then a pro
E031 Burner overheated Call a pro
E046 Limit control fault Call a pro
E047 Exhaust temperature sensor fault Call a pro
E060 Dual venturi fault Call a pro
E109 Fan motor fault Safe checks first, then a pro
E110 Abnormal air pressure (blocked vent or intake filter) Safe checks first, then a pro
E407 Hot water outlet temperature sensor fault Call a pro
E421 Cold water inlet temperature sensor 1 fault Call a pro
E432 Cold water inlet temperature sensor 2 fault Call a pro
E434 Water adjustment valve fault Call a pro
E438 Circulation pump fault Safe checks first, then a pro
E439 Flow sensor fault Call a pro
E441 Hot water inlet temperature sensor 2 fault Call a pro
E445 Bypass mixing valve fault Call a pro
E515 Circuit board fault Safe checks first, then a pro
E517 DIP switch setting error Call a pro
E593 Front panel button fault Call a pro
E594 Memory chip (EEPROM) fault Call a pro
E615 Input and memory fault Call a pro
E736 Cascade communication fault Call a pro
E740 Outdoor temperature sensor fault Call a pro
E760 Flushing or service reminder Call a pro
E762 Vent pipe not fully inserted Call a pro
E773 Wrong gas type detected or gas connection fault (depends on model) Call a pro
E782 Main panel communication fault Call a pro
E785 Flow switch or sensor fault Call a pro
E788 Gas type setting mismatch Call a pro

Models in this range