Noritz EZ Series & NCC199CDV error codes
These share a service manual with the NRC663-FSV and they do not share its code table — Noritz prints two separate tables in the same document, and reading the wrong one gives the wrong answer. This is the table with two high limit switches instead of one (code 20 on the heat exchanger, code 21 in the burner chamber), two heat exchanger thermistors instead of one (inlet 36 and outlet 33), and the two water servos, 65 and 66. It is also the only table on this site with **code 13: an external carbon monoxide alarm wired to the appliance has gone off.** That is not a diagnostic code in the ordinary sense and the page for it says so. Codes here appear with an "F" in front when they come from the secondary unit of a Quick Connect multi-system — F32 is a code 32 on the other heater, not a different fault.
Not your models? Check the model-number decoder before you read the table below — the code numbers repeat across series and the meanings do not.
| Code | Error | Verdict |
|---|---|---|
| 10 | Combustion fault recorded in history | Call a pro |
| 11 | Ignition failure | Call a pro |
| 12 | Flame rod does not detect flame | Call a pro |
| 13 | External carbon monoxide alarm triggered | Emergency — stop |
| 15 | Abnormally high input temperature | Call a pro |
| 16 | Abnormally high output temperature | Call a pro |
| 20 | Heat exchanger high limit switch triggered | Call a pro |
| 21 | Burner chamber high limit switch triggered | Call a pro |
| 30 | Air thermistor fault | Part replacement |
| 31 | Cold water thermistor fault | Part replacement |
| 32 | Hot water thermistor fault | Part replacement |
| 33 | Heat exchanger outlet thermistor fault | Part replacement |
| 35 | Exhaust thermistor fault | Call a pro |
| 36 | Heat exchanger inlet thermistor fault | Part replacement |
| 61 | Fan motor fault | Call a pro |
| 65 | Main water servo fault | Part replacement |
| 66 | Bypass water servo fault | Part replacement |
| 70 | Circuit board fault | Part replacement |
| 71 | Gas valve drive circuit fault | Call a pro |
| 72 | Flame rod circuit fault | Call a pro |
| 73 | Circuit board setting fault | Call a pro |
| 76 | Multi-system communication error | Part replacement |
| 90 | Combustion fault, unit shuts off | Call a pro |
| 94 | Exhaust temperature too high | Call a pro |
| 760 | Remote controller communication fault | Part replacement |
| C1 | Service reminder | DIY fix |
Every entry above is transcribed from the manufacturer's diagnostic documentation for this exact series, with the source cited on each code page.
Other Noritz series
Different series, different code table — if your unit isn't a EZ Series & NCC199CDV, check yours: