Code 12 means the heater lights and then loses the flame. In California, check one thing Noritz specifically calls out: the earthquake gas shutoff.
Safety first
If you smell gas, do not light anything or touch electrical switches. Leave the house and call SDG&E or 911 from outside. Manufacturers reserve gas, burner, venting and internal electrical work for qualified technicians.
Causes Noritz lists
- A dirty flame rod.
- Not enough gas or low inlet gas pressure.
- Exhaust being drawn back into the air intake.
- Wrong vent type or damaged vent O-rings.
What you can safely check
- Gas is on and other gas appliances work.
- Whether an earthquake shutoff valve near the gas meter has tripped. Have the gas company or a plumber reset it rather than doing it yourself.
- Outside intake and exhaust terminations are clear.
When to call a plumber
Gas pressure testing, flame rod cleaning and venting repairs are licensed contractor work, as Noritz recommends.
General information, not professional or legal advice; follow your manufacturer's manual, and your installer and local permit office have the final word. Sources:Noritz Help Center, Error Code 12; Noritz, Common Noritz Tankless Error Codes. SD Water Heaters is not affiliated with any manufacturer; brand names are used only to identify products, and codes can differ by model, so confirm in your own manual.
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