Takagi Condensing Code 031
Incorrect DIP switch settings. The DIP switches on the computer board are in a combination the heater does not accept. Takagi's own note is that gas type is a common DIP switch error, that most other switches should be left on their default unless the installation requires otherwise, and that Easy-Link systems need switch 10 on the right bank ON for the master unit and OFF for every slave.
Call a proThe verdict
Call a licensed plumber
A configuration fault rather than a broken part, which normally makes it cheap — but one of the switches sets the gas type, and that is not a setting to experiment with. If the unit was installed, converted, or had a board replaced recently, call that installer back.
Typical cost: $0–$400
US estimate for parts and labor. Prices vary by region and by who does the work — see how we estimate costs.
What the manual says
The meaning above is transcribed from the manufacturer's diagnostic documentation for the Condensing — not averaged across the brand.
Source: Takagi Condensing Models On-Demand Water Heater Troubleshooting Guide (p. 13), read Aug 2026 — the manufacturer's own documentation for this exact series.
What you can safely check
Before anything else: if you smell gas, stop here, leave, and call your gas utility.
- If the unit was installed, converted between fuels, or serviced recently, contact whoever did that work — this code points at it.
- Find out what your house actually runs on: natural gas from a meter, or propane from a tank.
- Do not open the unit to change switch settings yourself.
Frequently asked questions
Which switch is most often wrong?
Takagi names it: gas type. It is the setting that has to change when a unit is converted between natural gas and propane, and the one most likely to be missed.
Code 031 on other Takagi series
The same code number can mean something different on another series — make sure you're reading the page for your exact unit:
Don't confuse this with
One other Takagi Condensing code points at a switch too. They are different components in different places, and ordering a part against the wrong one is the most common way this fault gets expensive: