Noritz Error Codes — Quick Reference
Noritz tankless water heaters display fault codes on the front-panel display or on a remote controller. Two-digit codes are standard across all Noritz product lines (NRCP, NRC, NR, NCC, EZ series). Most codes require pressing the RESET button after correcting the fault.
| Code | Meaning | Quick Fix |
|---|---|---|
| 10 | Abnormal exhaust temperature | Check venting; flush HX if scaled |
| 11 | Ignition failure | Check gas, igniter, gas valve |
| 12 | Flame loss during operation | Gas pressure fluctuation; flame sensor |
| 14 | Thermal fuse open | Overheating; non-resettable, needs tech |
| 16 | Over-temperature safety | Scale in HX; check flow rate |
| 29 | Condensate drain blocked | Clean condensate neutralizer/trap |
| 31 | Cold water inlet thermistor | Replace thermistor |
| 32 | Hot water outlet thermistor | Replace thermistor |
| 33 | Heat exchanger thermistor | Replace thermistor |
| 34 | Combustion air thermistor | Replace thermistor |
| 61 | Fan motor fault | Check fan motor |
| 71 | Gas valve solenoid fault | Check solenoid coils |
| 90 | Combustion abnormality | Check gas/air ratio; call tech |
| 92 | Neutralizer needs service | Service condensate neutralizer |
Most Common Codes
Code 11: Ignition Failure
Noritz could not ignite the burner. Confirm: gas valve is on, meter is active, and no other large gas appliances are running simultaneously (pressure drop issue). On NRC and NRCP models, also verify the combustion air intake screen is clear of debris or insect nests.
Code 12: Flame Loss
The burner lit but flame went out mid-cycle. Intermittent gas pressure is the primary cause. Test by running the unit and simultaneously measuring gas pressure at the test port with a manometer — pressure should hold above 4” WC for natural gas. If pressure drops during firing, contact the gas utility.
Code 16: Over-Temperature
Heat exchanger is running too hot. On Noritz units installed in hard water regions, scale accumulation inside the copper/stainless HX is common after 3–5 years without maintenance. Noritz recommends annual descaling flush. Connect a pump to the service valve connections on the cold inlet and hot outlet and circulate white vinegar for 45 minutes.
Code 29: Condensate Drain Blocked
On condensing Noritz models (NCC, NRCP series), the condensate drain neutralizer collects acidic water condensed from combustion gases. When the neutralizer is clogged or the drain tube kinked, water backs up and trips the float switch. Inspect the drain tube from the unit to the drain — clear any kinks or blockages. If the neutralizer media is exhausted (limestone dissolved away), replace it.
Code 10: Abnormal Exhaust Temperature
The exhaust temperature sensor detected unusually high flue temperatures, indicating a scale-blocked heat exchanger or a venting restriction. Check the exhaust vent pipe for blockage (bird nests are common in horizontal through-wall vents). If the vent is clear, flush the heat exchanger.
Code 90: Combustion Abnormality
The control board detected abnormal combustion — usually incorrect gas/air ratio. This can be caused by: incorrect gas type setting (unit set for natural gas but connected to LP, or vice versa), damaged burner, or a failing proportional gas valve. This code requires technician diagnosis.
Parts Often Needed
| Part | Notes |
|---|---|
| Inlet thermistor | Amazon | Noritz PC-R09A or model-specific |
| Flame sensor rod | Amazon | Noritz model-specific |
| Condensate neutralizer | Amazon | Noritz CM-200 or compatible |
| Fan motor | Amazon | Model-specific; match by unit label |
When to Call a Pro
Code 14 (thermal fuse), code 71 (gas valve solenoid), and code 90 (combustion abnormality) require certified technician service. Noritz recommends annual professional maintenance regardless of whether any codes appear.