Disclaimer

Not professional advice

Tankless Codes publishes general reference information about tankless water heater error codes, compiled from manufacturer documentation. It is not professional plumbing, gas-fitting, electrical, or HVAC advice, and reading it does not create any professional relationship. For diagnosis and repair of your specific unit, consult a licensed professional or the manufacturer.

Gas safety comes before everything on this site

This site never provides instructions for working on gas lines, venting or exhaust systems, or for bypassing an appliance's safety lockouts. Where an error code involves gas, ignition, or exhaust, the only correct action is to stop and call a licensed professional. Repeated safety lockouts are the unit protecting you — do not keep resetting it.

DIY work is at your own risk

The "homeowner-safe checks" on some pages are limited to actions like checking water flow, power, and inlet filters, or performing a manufacturer-described descaling flush. If you choose to do them, you do so at your own risk. Local plumbing and gas codes may require permits or licensed work; DIY repairs can also affect your manufacturer warranty.

How we estimate costs

Part prices and repair cost ranges shown on code and part pages are typical US figures, intended to help you tell a fair quote from a bad one — not to predict your invoice. Ranges are built from two things: the typical retail price of the component involved, and typical US labor for the work around it (commonly one to two hours for a component replacement, plus a diagnostic call).

A range's low end usually assumes the cheapest realistic outcome — often a clean, a reset, or a part you can fit yourself. The high end assumes the most expensive component on the manufacturer's troubleshooting list for that code actually needs replacing. Real prices vary widely by region, installer, whether the unit is under warranty, and how accessible it is. Always get a written quote.

Affiliate disclosure

Some pages may contain affiliate links, always marked as sponsored. If you purchase through one, we may earn a commission at no extra cost to you. Recommendations are based on the fault, never on the commission.

Trademarks & independence

Rinnai, Navien, Rheem, Noritz, Takagi, and other brand names are trademarks of their respective owners. Tankless Codes is an independent publication and is not affiliated with, sponsored by, or endorsed by any manufacturer.