Noritz Error Code 91: Gas conversion not done correctly (Tankless)
Noritz error code 91 on a tankless water heater means: Gas conversion not done correctly. It is also called Noritz diagnostic code 91.
Homeowner? What Noritz code 91 means for you
Stop and call Your tankless water heater is reporting: Gas conversion not done correctly. This code is a safety shutdown. Turn the tankless water heater 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 that gas reaches the house: other gas appliances work, or the propane tank is not empty.
- Make sure the heater is plugged in and its breaker is on. In winter, keep the power on: it protects the unit from freezing.
Call (647) 657-2977Book a service call
Licensed technicians serving Vaughan, Toronto and the GTA.
What does Noritz error code 91 mean?
EZ/NRCR: the unit's gas conversion was not completed correctly.
Applies to: Noritz EZ111/EZ98/EZ71 and NRCR111/NRCR92
Common causes of Noritz code 91
- LP orifice installed but gas type not changed in the app/display (or the reverse)
- Gas conversion connector missing (NG to LP)
- Wrong conversion kit
Noritz models that use code 91
EZ71DVEZ98DVEZ111DVNRCR92DVNRCR111DV
Other Noritz Tankless codes
All Noritz Tankless Water Heater error codes →
Noritz code 91: homeowner questions
What does Noritz code 91 mean?
Gas conversion not done correctly. EZ/NRCR: the unit's gas conversion was not completed correctly.
Is it safe to keep using my tankless water heater with code 91?
No. Code 91 is a safety shutdown, so keep the tankless water heater off until a licensed technician has checked it.
Can I reset Noritz code 91 myself?
Do not keep resetting it. Repeated resets can hide a safety problem; a licensed technician needs to find the cause.
Who can fix Noritz code 91 near me?
Aurora Star Tech Inc. repairs Noritz tankless water heaters 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
Troubleshooting guides
- No hot water All brands · Tankless Water Heater
- Water temperature fluctuates All brands · Tankless Water Heater
- Cleaning ignition and flame rods - Noritz Noritz · Tankless Water Heater
- Cleaning the fan and burner - Noritz EZ/NRCR/CDV Noritz · Tankless Water Heater
- Descaling (flushing) the heat exchanger - Noritz Noritz · Tankless Water Heater
- Draining to prevent freezing - Noritz EZ/NRCR Noritz · Tankless Water Heater
- Field gas conversion NG to LP - Noritz NRCR/EZ Pro Noritz · Tankless Water Heater
- Heat exchanger replacement - Noritz NRC111 / NCC199 Noritz · Tankless Water Heater
- Heater does not fire when hot water is opened - Noritz tankless Noritz · Tankless Water Heater
- Recirculation not working or hot water slow - Noritz NRCR Noritz · Tankless Water Heater
- Water not hot enough or temperature fluctuates - Noritz tankless Noritz · Tankless Water Heater
Source: Noritz EZ/NRCR Owner's Guide (Rev. 10-25), Checking for error conditions / Gas conversion, p.31, 33; Noritz NRCR Pro training (NRCR92/NRCR111, Printable V3), Field gas conversion, p.3-6. 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.