Navien Error Code E773: Improper gas type detected (Combi Boiler)
Navien error code E773 on a combi boiler means: Improper gas type detected. It is also called Navien diagnostic code E773.
Homeowner? What Navien code E773 means for you
Stop and call Your combi boiler is reporting: Improper gas type detected. This code is a safety shutdown. Turn the combi boiler off and call a licensed technician. Do not keep resetting it. If you smell gas, leave the house and call your gas utility or 911 from outside.
Safe things you can check yourself
- Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
- Make sure the unit has power: its on/off switch (often looks like a light switch near the unit) is ON and the breaker in the electrical panel is not tripped.
Call (647) 657-2977Book a service call
Licensed technicians serving Vaughan, Toronto and the GTA.
What does Navien error code E773 mean?
The boiler detected a mismatch between the gas type set at install and the gas actually connected. The manual notes detection takes time and may also trigger from measuring tolerance with the correct gas. NFC-H manual lists the reset type as: Parameter reset.
Applies to: Navien fire-tube combi boilers, NFC-H series (NFC-250/200H, NFC-250/175H) and NCB-H combi boilers (NCB-250/150H, NCB-240/130H, NCB-240/110H, NCB-190/080H, NCB-190/060H)
Common causes of Navien code E773
- Gas type DIP switch (SW2 #1) not matching the supply
- Conversion kit / orifice not installed or wrong kit
- Measurement tolerance (false trip)
Navien models that use code E773
NCB-190/060HNCB-190/080HNCB-240/110HNCB-240/130HNCB-250/150HNFC-250/175HNFC-250/200H
Other Navien Combi Boiler codes
All Navien Combi Boiler error codes →
Navien code E773: homeowner questions
What does Navien code E773 mean?
Improper gas type detected. The boiler detected a mismatch between the gas type set at install and the gas actually connected. The manual notes detection takes time and may also trigger from measuring tolerance with the correct gas. NFC-H manual lists the reset type…
Is it safe to keep using my combi boiler with code E773?
No. Code E773 is a safety shutdown, so keep the combi boiler off until a licensed technician has checked it.
Can I reset Navien code E773 myself?
Do not keep resetting it. Repeated resets can hide a safety problem; a licensed technician needs to find the cause.
Who can fix Navien code E773 near me?
Aurora Star Tech Inc. repairs Navien combi boilers in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.
Homeowner help: Tankless Water Heater No Hot Water: What to Check · Boiler Not Heating: What to Check
Troubleshooting guides
- Hot water is cold or turns cold - Navien NCB-H Navien · Combi Boiler
- Hot water not hot enough or too hot - Navien NCB-H Navien · Combi Boiler
- No space heating - Navien NCB-H Navien · Combi Boiler
- No water from hot water tap - Navien NCB-H Navien · Combi Boiler
Source: Navien NCB-H Installation & Operation Manual, 11.7 Understanding Error Codes, p.129-130; Navien NFC-H Installation Manual, 11.7 Understanding Error Codes, p.127-128. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.