How to Reset a Takagi Tankless Water Heater
On this page (5 sections)
The Short Answer: Takagi tankless heaters don’t have a customer reset button. For most error codes, the reset is turning the unit off and back on, with the remote’s power button or by briefly cutting its 120-volt power. Write down the code first, fix any obvious cause such as a closed gas valve or blocked vent, then reset once. If the code returns, the unit needs service.
Before you reset
The error code is the most useful thing the technician will have, and on many units it disappears when power is cut. Write down or photograph:
- The code number on the remote controller or the unit’s display.
- The model number from the rating plate (for example T-KJr2, T-H3, or T-K4).
- What was happening: whether the code appeared at startup, during a long shower, or after a storm or cold night.
Code meanings differ between Takagi generations, so match the code against the manual for your model. On many Takagi units, 11 relates to ignition and 12 to flame loss, but confirm that in your manual before acting on it. See Takagi tankless water heater problems and Takagi code 111 for model-specific guidance.
How to reset
- Fix what you can safely. Check that the gas supply valve to the heater is open and other gas appliances work, that the outdoor vent termination or intake is clear, and that the heater’s power cord or switch has power.
- Turn it off. Use the power button on the remote if there is one; otherwise switch off the breaker or unplug the unit.
- Wait a short time, then restore power.
- Open a hot faucet and see whether the burner lights and the code stays clear.
When a reset isn’t the answer
| Situation | Why to stop |
|---|---|
| The same code returns within a few uses | The cause is still present |
| A code your manual describes as abnormal combustion or a hard lockout | Some lockouts can only be cleared at the control board by a technician, after the cause is fixed |
| Gas smell, soot, or a bang at ignition | Combustion or gas supply problem; leave it off |
| Water leaking from the unit | Possible freeze damage or a failed heat exchanger; see Takagi tankless leaking |
| Overheating codes on hard water | Scale buildup in the heat exchanger needs flushing |
Each failed ignition attempt sends unburned gas through the burner. Resetting repeatedly to force it to light is unsafe.
What a technician will check
A technician reads any stored error history, measures gas pressure at the unit with the burner at full fire, inspects the igniter and flame rod, and checks the fan, vent, and air intake. For overheating and flow-related codes they check the inlet filter and the heat exchanger for scale and may flush it. Some codes, especially those for abnormal combustion, require cleaning the burner before the unit is cleared to run again.
Frequently Asked Questions
Q: Where is the reset button on a Takagi? A: There isn’t a customer reset button. The power cycle described above is the reset. Board-level reset procedures in service literature are for technicians.
Q: How long should I leave the power off? A: A brief interruption is usually enough for the control to restart. If your manual gives a specific time, follow it.
Q: The display is blank and nothing happens. Is that a lockout? A: No. A blank display means the unit isn’t getting power or the controller has failed. Check the outlet, breaker, and any GFCI first.
Manuals and supporting references
These links distinguish general safety information from model-specific documentation. A manual directory helps you locate your unit’s instructions; it does not establish that every model uses the same parts, codes, or test values.
- PG&E: recognizing and responding to a gas leak (opens in a new tab)Emergency actions for suspected fuel-gas leaks.
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