Takagi tankless water heater code 031
Incorrect DIP switch settings. Code 031 means the same thing on all 2 Takagi series documented here — but the fix, and what it costs, is still worth reading for your exact unit.
What code 031 means on each Takagi series
| Series | What it means | Verdict | Typical cost |
|---|---|---|---|
| Condensing | Incorrect DIP switch settings | Call a pro | $0–$400 |
| Non-Condensing | Incorrect DIP switch settings | Call a pro | $0–$400 |
Each row opens the full page for that generation. We hold manuals for Condensing and Non-Condensing, and each one gets its own reading of code 031 — what Takagi documents, what you can safely check yourself, and what the repair should cost.
What each manual actually says
The table above compares 2 series in four columns, which is enough to route you and not enough to explain anything. This is the Takagi wording behind each row, one entry per manual, so you can see where the 2 readings of code 031 agree and where they part company.
Condensing — 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.
Non-Condensing — Incorrect DIP switch settings
The DIP switches on the computer board are in a combination the heater does not accept. Gas type is the setting most often wrong, and it is the one that matters most. On a T-K4 or T-KJr2 this shows as 03 on the remote, or one flash of the red LED.
Does it matter which Takagi you have?
Condensing and Non-Condensing all route code 031 the same way: a professional, at $0–$400. That makes it one of the Takagi numbers you can act on before working out which unit you own.
What to check first, whatever your series
These checks are on the manufacturer's list for every Takagi series that reports code 031, so they are safe to work through before you have identified your exact unit. They also cost nothing.
- 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.
That is 2 of the 3 checks documented for code 031. The rest differ by generation, so if none of those explains it, go to your own series above.
Which Takagi do you have?
On the 2 series that report code 031, the model number on the rating label starts T — match yours against the 3 listed below. You can also use the full model-number decoder.
Where this comes from
Source: Takagi Condensing Models On-Demand Water Heater Troubleshooting Guide (p. 13), read Aug 2026 — the manufacturer's own documentation for this Takagi range.
Source: Takagi Non-Condensing Models On-Demand Water Heater Troubleshooting Guide (p. 12), read Aug 2026 — the manufacturer's own documentation for this Takagi range.
Parts, guides and symptoms behind code 031
Code 031 on these 2 Takagi series points at 2 parts, each named by the manufacturer's own procedure for this code.