Navien Error Codes

Find troubleshooting guides for all Navien error codes.

10 error codes across 1 appliance types

Waterheater

Code	Meaning	Severity
E001	The unit failed to establish a flame on the first ignition attempt. E001 is an early-stage ignition fault that precedes E003, which fires after all 3 attempts fail. high	high
E003	The unit attempted to ignite 3 times and failed to detect a flame on any attempt. The gas valve, igniter, and flame rod are the primary components to inspect. high	high
E012	The burner flame was established successfully but was lost while the unit was actively heating water. This is distinct from E003, which means ignition never occurred at all. high	high
E110	The unit detected an exhaust or air supply restriction. E110-01 indicates an external vent termination blockage; E110-02 indicates an internal air/exhaust pressure imbalance. high	high
E302	The PCB detected a flame signal from the flame rod when the gas valve is confirmed closed and the unit should be off. This is a safety lockout that prevents the unit from operating until the false signal is resolved. moderate	moderate
E762	The outlet water temperature exceeded 190 degrees Fahrenheit (87.7 degrees Celsius), triggering a high-limit safety lockout. The unit shuts off to prevent scalding and thermal damage to components. high	high
E773	The exhaust gas temperature exceeded the safe thermal limit. A thermal fuse or high-limit sensor in the exhaust path tripped due to excessive heat, causing a safety lockout. high	high
HUB	Reference hub covering all Navien NPE and NCB series error codes with diagnosis and repair guidance. low	low
NO-HOT-WATER	Error Codes and Flow Sensor Fix medium	medium
RESET	Guide covering all three reset methods for Navien NPE and NCB series: soft reset via Info button, hard reset via power cycle, and factory reset via controller menu. low	low