Noritz tankless water heater error codes
7 codes that Noritz publishes for its tankless water heaters, each with what it means, the likely cause, what you can safely check and when to call a licensed professional. Tap your code:
If you smell gas
Stop: do not reset, relight or check anything on this page. Noritz’s own words, from the cover page of the EZ111DV/EZ98DV Owner’s Guide, under “What to do if you smell gas”:
- Do not try to light any appliance.
- Do not touch any electrical switch; do not use any phone in your building.
- Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s instructions.
- If you cannot reach your gas supplier, call the fire department.
Calling from a neighbor’s phone means leaving the building first. Source: EZ111DV / EZ98DV Condensing Tankless Gas Water Heater Owner’s Guide (SBB80T9-1, Rev. 01/17): gas-smell instructions and troubleshooting
Tankless gas water heater: do only the owner checks its manual gives for that code — open the gas and water shut-off valves, check a propane tank has gas, clean a filter the way the manual shows you, clear snow or debris from the vent ends outside, turn it off and on at the controller. Leave gas pressure, the burner, the gas valve, wiring and circuit boards alone. Everything else is for a licensed professional — in the manuals’ words, a qualified installer, service agency or the gas supplier. If you smell gas, do none of the checks: follow the maker’s gas-smell instructions at the top of the page. Codes that need one are marked Licensed pro.
Read this first
Noritz tankless water heaters flash a number on the remote controller or the display window, and the operation light flashes with it. The owner’s guides we downloaded from Noritz do not give their table’s code numbers in readable text, so this page takes its codes from the two articles Noritz publishes on noritz.com about its most common error codes — the seven codes of 2015 (11, 12, 16, 29, 73, F76, 90) and the 2022 update by its service-training supervisor on 11, 12 and 90. Noritz’s own advice in both: some fixes are simple, but err on the side of caution and contact a licensed contractor.
11 Ignition failure
- What it means
- The heater is not firing up to heat the water. Noritz explains that ignition needs three things — air, spark and gas — and code 11 means one of them is missing.
- Likely cause
- Insufficient gas supply (for example an empty propane tank or a disruption in the gas line), insufficient airflow, or debris on the ignition plug.
- What you can safely check
Tankless gas water heater: do only the owner checks its manual gives for that code — open the gas and water shut-off valves, check a propane tank has gas, clean a filter the way the manual shows you, clear snow or debris from the vent ends outside, turn it off and on at the controller. Leave gas pressure, the burner, the gas valve, wiring and circuit boards alone.
- Check that the gas is turned on — Noritz’s first step.
- On propane, check there is gas in the tank.
- Noritz’s owner’s guide adds, for an ignition error: turn the unit off, open a hot water tap, and turn the unit back on; if the number does not flash again, the problem is solved.
- When to call a licensed professional
- Then call a licensed contractor: Noritz says they will check the gas valve, the gas type and pressure (with a digital manometer), the exhaust vent and the ignition plug. A code 11 during draining is normal, per the owner’s guide.
Source: Noritz, How To Resolve The Seven Most Common Noritz Tankless Error Codes (Noritz blog, 16 November 2015) Checked 2026-09-29.
12 Flame loss: the flame does not stay lit
- What it means
- The burner lights but does not stay lit, so the water does not reach the set temperature. Noritz notes a tankless heater favors temperature over volume, so you may get hot water at much lower flow and pressure.
- Likely cause
- Lack of gas or airflow. On propane a low tank causes flame loss; in winter an undersized gas supply shared with other appliances weakens the flame.
- What you can safely check
Tankless gas water heater: do only the owner checks its manual gives for that code — open the gas and water shut-off valves, check a propane tank has gas, clean a filter the way the manual shows you, clear snow or debris from the vent ends outside, turn it off and on at the controller. Leave gas pressure, the burner, the gas valve, wiring and circuit boards alone.
- On propane, check how much gas is left in the tank.
- When to call a licensed professional
- Call a licensed contractor or Noritz customer care: Noritz’s fix is measuring the gas pressure with a digital manometer.
Source: Noritz, Common Noritz Tankless Error Codes: Updated (Noritz blog, 6 June 2022) Checked 2026-09-29.
16 Outlet water temperature spike
- What it means
- A sharp spike in outlet water temperature.
- Likely cause
- Often scale build-up from hard water, which lowers heat transfer and makes the unit burn hotter to compensate.
- What you can safely check
Nothing for the owner to check: this one is for a licensed professional.
- When to call a licensed professional
- Licensed pro Contact a licensed contractor: Noritz says descaling or a water softener may resolve it, and the contractor should confirm that is the cause.
Source: Noritz, How To Resolve The Seven Most Common Noritz Tankless Error Codes (Noritz blog, 16 November 2015) Checked 2026-09-29.
29 Condensate drainage problem
- What it means
- On a condensing heater, the condensate (acidic water from the exhaust, drained through a neutralizer) is not draining. The code stops the burner from flooding.
- Likely cause
- A blocked condensate drain line or incorrectly installed condensate drain piping.
- What you can safely check
Nothing for the owner to check: this one is for a licensed professional.
- When to call a licensed professional
- Licensed pro Call a licensed contractor to check that the condensate drain line is routed properly and clear.
Source: Noritz, How To Resolve The Seven Most Common Noritz Tankless Error Codes (Noritz blog, 16 November 2015) Checked 2026-09-29.
73 Circuit board settings
- What it means
- The circuit board’s settings are wrong.
- Likely cause
- Changing a jumper or DIP switch while the heater has power, or an incorrectly programmed circuit board.
- What you can safely check
Tankless gas water heater: do only the owner checks its manual gives for that code — open the gas and water shut-off valves, check a propane tank has gas, clean a filter the way the manual shows you, clear snow or debris from the vent ends outside, turn it off and on at the controller. Leave gas pressure, the burner, the gas valve, wiring and circuit boards alone.
- Unplug the heater for 30 seconds, then plug it back in — Noritz’s action.
- When to call a licensed professional
- If 73 persists, call a licensed contractor.
Source: Noritz, How To Resolve The Seven Most Common Noritz Tankless Error Codes (Noritz blog, 16 November 2015) Checked 2026-09-29.
F76 Communication failure between two linked heaters
- What it means
- Two tankless heaters joined with Noritz’s Quick Connect Cord have lost communication.
- Likely cause
- More than one remote control connected to two Quick-Connected units.
- What you can safely check
Tankless gas water heater: do only the owner checks its manual gives for that code — open the gas and water shut-off valves, check a propane tank has gas, clean a filter the way the manual shows you, clear snow or debris from the vent ends outside, turn it off and on at the controller. Leave gas pressure, the burner, the gas valve, wiring and circuit boards alone.
- Make sure only one remote control is connected when two units are linked.
- When to call a licensed professional
- If F76 continues, contact a licensed contractor.
Source: Noritz, How To Resolve The Seven Most Common Noritz Tankless Error Codes (Noritz blog, 16 November 2015) Checked 2026-09-29.
90 Combustion abnormality
- What it means
- The heater makes three attempts to reach the set temperature; after the third failure it shows 90. The air and fuel mixture is wrong.
- Likely cause
- Two causes, per Noritz: gas pressure that is too low (as with 11 and 12), or an internal problem needing maintenance — a blocked air intake or exhaust route, or dirt and lint in the fan motor.
- What you can safely check
Nothing for the owner to check: this one is for a licensed professional.
- When to call a licensed professional
- Licensed pro You need a licensed contractor: Noritz says they will check the gas pressure, the venting length and the DIP switches, and clean dirt and lint out of the unit with an air compressor if the problem is internal.
Source: Noritz, Common Noritz Tankless Error Codes: Updated (Noritz blog, 6 June 2022) Checked 2026-09-29.
A code that is not listed here
Noritz heaters have more codes than the seven here; the full list is in your model’s owner’s guide and installation manual, and Noritz says to contact it if any other error code appears or a code returns after the actions given. If you open a hot tap and the heater does nothing and shows no code, Noritz’s 2022 article explains why: a tankless heater only starts, and only shows codes, once it detects a flow of at least 0.5 gallons per minute.
We list only codes the source below states. If your code is not here, it may belong to a model the source does not cover: your model’s manual is the authority.
Related pages
Source
Every code on this page comes from these pages, published by Noritz and read on the date shown. Meanings are written in our own words; nothing is taken from other makes, other models or third-party code sites.
- Noritz: How To Resolve The Seven Most Common Noritz Tankless Error Codes (Noritz blog, 16 November 2015) Checked 2026-09-29.
- Noritz: Common Noritz Tankless Error Codes: Updated (Noritz blog, 6 June 2022) Checked 2026-09-29.
- Noritz: EZ111DV / EZ98DV Condensing Tankless Gas Water Heater Owner’s Guide (SBB80T9-1, Rev. 01/17): gas-smell instructions and troubleshooting Checked 2026-09-29.