Tankless Water HeaterTroubleshooting2026-01-29
Tankless Water Heater Error Codes Explained
Tankless error codes point to ignition, flow, venting, or scale issues — here's how to read them.
Tankless water heaters self-diagnose and display error codes. Understanding the categories helps you respond correctly.
Common code categories
Ignition/flame codes, gas-supply codes, flow-sensor codes, venting/air codes, and over-temperature codes are the main families. Brands like Navien, Rinnai and Noritz each have their own numbering.
What to do
Note the exact code and brand, check obvious items (gas on, vents clear, inlet filter clean), and call with the code for faster repair — never bypass safety lockouts.
Key takeaways
- Record the exact code and brand
- Check gas, venting and the inlet filter
- Scale-related codes mean it's time to descale
- Don't bypass safety lockouts
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Frequently asked questions
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