Noritz Tankless Water Heater Error Codes: Full List & Meanings

Every Noritz tankless water heater error code we have verified against Noritz's own support pages, with its official meaning. This list covers nrcr condensing tankless water heaters (owner's guide). Codes vary by model, so confirm in your owner's manual. Support: Noritz America Technical Support, 1-866-766-7489.

Smell gas? Leave the building now. Do not touch light switches, phones or appliances inside. Call your gas utility or 911 from outside. CO alarm sounding or headache, dizziness or nausea? Get everyone outside and call 911. Gas valves, burners, venting and wiring are for a licensed technician only. See our safety policy.

Codes by system

Heating

Venting / airflow

Water fill

All Noritz tankless water heater error codes

Codes marked "Reset only" or "Service" have no separate page because the manufacturer publishes no owner fix beyond a reset or a service call.

Code	Official meaning	System	Owner action
11	Ignition failed.	Heating	Owner checks
90	The air supply vent (indoor combustion air), exhaust vent or condensate drain may be clogged, or gas pressure is low. Also: 901, 902	Venting / airflow	Owner checks
06	Recirculation abnormality (NRCR models only). Also: 061, 062	Water fill	Owner checks
91	The manufacturer lists 91 as: gas conversion not performed correctly; contact the installer.	Heating	Service
C1#	The manufacturer lists C1# as: descaling reminder (C11–C19): flush the heat exchanger per the installation manual or contact Noritz.	Status / reminder	Service

Symptoms

Sources

https://noritz.com/assets/nrcr_ownersguide.pdf (official)

Last reviewed: October 20, 2026. ErrorCodePro is not affiliated with Noritz.