How to Reset a Takagi Tankless
The Short Answer: Most Takagi (and AO Smith-badged twin) tankless units reset by killing 120-volt power for 10–30 seconds — switch, then breaker if needed — not by holding a hidden red button. Photograph the code first. One reset after you clear a vent, filter, or GFCI. Do not reset a 13 (remaining flame) or a unit that smells like gas. Full code list: Takagi problems.
Licensed local technicians
Takagi locked out after a reset loop?
Connect with a licensed 24/7 technician in your zip code right now.
Search Intent & The Real Problem
The shower died. A neighbor said “hit the reset.” You cannot find a button like a tank ECO. Takagi lockouts live in the PCB. Power-cycling clears a latch so the unit can try again. It does not fix a blocked vent, a 1/2” gas whip, or scale. Ten resets in a morning is how igniters glaze.
What other guides get wrong
They show a tank-style ECO button on a Takagi jacket. Many T-KJr2 / T-K4 / T-H3 units have no customer high-limit button on the front. They also treat reset as the repair. Reset is the last step, not the first.
Step-by-Step Troubleshooting
Step 1: Capture the code before you kill power
- What to look for: Two-digit code on the remote or PCB LED. 10 = air/exhaust. 11/12 = ignition/flame. 14/16 = overheat. 13 = remaining flame — stop.
- Required tools: Phone photo of the code and the rating plate.
If you reset first, you donated the only diagnostic the board had.
Step 2: Fix the obvious cause — then reset once
| Code | Do this first | Then reset? |
|---|---|---|
| 10 | Clear termination, condensate, bird screen | Once |
| 11 / 12 | Gas cock open, inlet screen, no wind in burner | Once |
| 14 / 16 | Scale / low flow — do not keep firing | After a proper flush or a tech |
| 13 | Shut gas, leave | No — licensed |
| None, just dead | GFCI / disconnect | Once if power was the issue |
- Required tools: Flashlight on the vent and the cold-side filter.
Step 3: The actual reset
- What to look for: Appliance switch off, wait 10–30 seconds, on. If the switch does nothing, the 120-volt disconnect or GFCI. Some remotes have a function that returns to factory temperature — that is not a lockout reset.
- Required tools: Your hand. No paperclip in the PCB.
Wait a full 30 seconds on stubborn latches. Five seconds is not a reset; it is a flicker.
Step 4: What a good reset looks like
- What to look for: Display returns, no code, unit fires on a hot-water call within the trial window, stable flame, no bang. A bang is delayed ignition — shut it down. Do not purge the gas line yourself.
- Required tools: One hot faucet, ears.
Step 5: When the code returns in minutes
- What to look for: Same 10/11/12/16 within one shower. The cause is still there. A second reset is not a procedure. A third is how you buy an igniter and a high-limit.
- Required tools: None. Call a licensed tech with the photo of the code.
When DIY Ends: Calling a Licensed Pro
Stop at code 13, gas smell, water on the board, repeated 11/12 after a clean filter, and any 16 after a recent flush (restricted exchanger). You may power-cycle once and clean the inlet screen. Combustion, gas pressure, and board replacement are licensed. Takagi/AO Smith will not love a heat exchanger that was reset through an overheat all weekend.
Frequently Asked Questions
Q: How do I reset a Takagi tankless water heater? A: Photograph the error, fix the obvious cause, then switch the unit off for 10–30 seconds (breaker if the switch is dead). There is often no tank-style red ECO button.
Q: Where is the reset button on a Takagi? A: Many models have none for the customer. The “reset” is a power cycle. If your specific SKU has a controller reset in the manual, use that — not a random button on the gas valve.
Q: Why does my Takagi keep needing a reset? A: The lockout cause is still present: vent, gas, scale, or flow. Repeated resets are a failure to diagnose, not a maintenance schedule.