Takagi Error Code 321: Inlet Temp Sensor
Warning: Your Takagi tankless water heater has detected a problem with its inlet water temperature sensor and has shut down to prevent potential damage. You will have no hot water until this is resolved.
How to Fix Takagi Code 321
- Step 1: Check the water heater's display for any other error codes. Note them down, as they may provide additional clues.
- Step 2: Reset the water heater by turning off the power at the breaker for 30 seconds, then turning it back on. This may clear a temporary error.
- Step 3: If the error persists after resetting, contact a qualified HVAC technician to diagnose and repair the issue.
How to Reset Takagi Code 321
- 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 321 mean?
The Takagi error code 321 indicates that the water heater's control board is receiving an unexpected signal from the inlet water temperature sensor. This sensor is responsible for measuring the temperature of the incoming cold water supply. The control board uses this information to properly modulate the burner and maintain a consistent output temperature. If the sensor is faulty, or the wiring is damaged, the control board won't know the incoming water temperature, and the unit will lock out for safety. This prevents the unit from overheating or operating inefficiently. It's important to address this issue promptly to restore hot water service and prevent potential damage to the unit.
Affected Models
Replacement Parts
| Part | OEM Number | Est. Cost |
|---|---|---|
| Inlet Water Temperature Sensor | TK10014 | — |
| 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 |
| 312 | Outlet Temp Sensor | Warning |
| 391 | Exhaust Temp Sensor | Warning |
| 510 | Gas Solenoid Valve | Critical |
| 610 | Fan Motor Fault | Warning |