Noritz 13
Noritz error code 13: CO alarm device
Short answer
Noritz error code 13 relates to the optional carbon monoxide (CO) alarm device that can be connected to the water heater. Noritz's knowledge base describes it as a malfunction with that CO alarm device. Because it involves carbon monoxide, treat any CO symptoms as an emergency before troubleshooting the code.
In this guide
Some Noritz installations include an optional CO alarm wired to the water heater, so the heater can respond if carbon monoxide is detected. Code 13 is tied to that device.
The meaning below comes from Noritz's own technical knowledge base. Noritz technical support: 866-766-7489.
Carbon monoxide is colorless and odorless. If anyone in the home has a headache, dizziness, nausea or confusion, or a CO alarm is sounding, leave the building right away and call 911 from outside. Do not reset the heater until a professional has checked it.
Two possibilities
- The CO alarm detected carbon monoxide. That points to a combustion or venting problem that needs immediate professional attention.
- The CO alarm device itself has a fault, such as a wiring problem, a disconnected sensor or a device at the end of its life.
What to do
- Rule out a real CO problem first. If in doubt, leave and call for help.
- Check any separate CO alarms in the home and test them.
- Call a qualified technician to inspect the venting, the combustion and the CO alarm device and its wiring.
Every home with a gas appliance should have working CO alarms near sleeping areas, independent of the water heater's own device.
Before you call
Have the model and serial number from the rating label ready, along with the exact code and when it appears: at startup, during use, or only at high demand. Mention any recent work on the gas, water or electrical supply and when the heater was last serviced. This helps the technician bring the right parts and often saves a second visit.
See every code on our Noritz error codes page.
Common questions
Is Noritz code 13 a carbon monoxide leak?
Not necessarily. It relates to the optional CO alarm device, which can report a fault with itself. Always rule out real CO first.
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Other Noritz codes
| Code | Meaning |
|---|---|
| 10 | Combustion abnormality (warning) |
| 11 | Ignition failure |
| 12 | Flame loss |
| 13 | Optional CO alarm device fault |
| 14 | Thermal fuse blown (severe overheat) |
| 16 | Outlet water temperature spiked too high |
| 20 | High limit switch tripped |
| 29 | Condensate drain problem (condensing models) |
| 67 | Air gas mixer (AGM) abnormality |
| 71 | Gas valve circuit abnormality |
| 90 | Combustion abnormality |
| 92 | Neutralizer near end of life (first warning) |
| 93 | Neutralizer at end of life |