Takagi Error Code 312: Outlet Temp Sensor
Warning: The tankless water heater has shut down due to a problem with the outlet temperature sensor. This will prevent hot water from being produced until the issue is resolved.
How to Fix Takagi Code 312
- Step 1: Reset the unit by turning off the power at the breaker for 30 seconds, then turn it back on. This may clear a temporary error.
- Step 2: Check the display for the error code again. If it reappears, the problem persists.
- Step 3: Contact a qualified HVAC technician to diagnose and repair the issue. Do not attempt to disassemble the unit yourself.
How to Reset Takagi Code 312
- Turn off the unit using the power button on the front panel.
- Turn off the gas supply valve.
- Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
- Restore power at the breaker, then open the gas valve.
- Turn the unit back on. If the error returns, the underlying issue needs repair.
What does 312 mean?
The Takagi 312 error code indicates a problem with the outlet temperature sensor. This sensor monitors the temperature of the water as it leaves the heat exchanger. The control board uses this reading to modulate the burner and maintain a consistent output temperature. If the control board doesn't receive a valid signal from this sensor, it will shut down the unit as a safety measure. This prevents the unit from overheating or delivering water at an unsafe temperature. A faulty sensor, wiring issues, or even a problem with the main control board can trigger this error. Because the unit has locked out, you will not have hot water until the problem is resolved.
Affected Models
Replacement Parts
| Part | OEM Number | Est. Cost |
|---|---|---|
| Outlet Temperature Sensor | TK190047 | — |
| Main Control Board | — | — |
Related Codes on Same Models
| Code | Description | Severity |
|---|---|---|
| 101 | Combustion Abnormality | Critical |
| 111 | Ignition Failure | Critical |
| 121 | Flame Failure | Critical |
| 200 | Overheating | Warning |
| 207 | Bypass Valve Error | Warning |
| 291 | Flow Rate Issue | Warning |
| 321 | Inlet Temp Sensor | Warning |
| 391 | Exhaust Temp Sensor | Warning |
| 510 | Gas Solenoid Valve | Critical |
| 610 | Fan Motor Fault | Warning |