HeatingCodesTakagi tankless error codes (T-KJr2, T-K4, T-D2)
These Takagi heaters report faults as a number on the remote controller, as a 7-segment display on the T-D2, or as a number of red LED flashes on the T-KJr2 and T-K4 board.
How to read the display
On the T-KJr2 and T-K4 the remote controller shows a two-digit code and the red LED on the board flashes a count that points to the same fault. On the T-D2 the board display and remote show a three-digit code (for example 111 instead of 11). The table gives both. Note that the LED count is not unique: Takagi lists three flashes for both ignition failure (11) and flame loss (12).
Takagi says to contact its technical service department for several of these problems, and to have the gas supply and manifold pressure checked by a qualified person.
Takagi code table
| Code | Meaning | What the document says |
|---|---|---|
| 03 (031) | Incorrect dipswitch settings | Gas type is a common dipswitch error. LED: 1 flash. |
| 10 (101) | Warning for the 99 error code (abnormal combustion) | LED: 5 flashes. Full explanation |
| 11 (111) | Ignition failure | The heater did not fire after three attempts. LED: 3 flashes. Full explanation |
| 12 (121) | Flame loss | Flames disappeared while the unit was supposed to be running. LED: 3 flashes. Full explanation |
| 31 (311) | Output thermistor | LED: 2 flashes. |
| 32 (321) | Inlet thermistor | LED: 2 flashes. |
| 39 (391) | Air-fuel ratio rod failure | LED: 2 flashes. |
| 51 (510) | Abnormal gas valves | LED: 6 flashes. |
| 55 | Abnormal solenoid gas valve | LED: 6 flashes. |
| 61 (611) | Abnormal fan motor | LED: 4 flashes. |
| 70 (701) | Computer board fault | LED: 1 flash. |
| 72 (721) | False flame detection | LED: 6 flashes. |
| 74 (741) | Remote controller communication failure | |
| 99 (991) | Abnormal combustion | Refer to error code 101 (10). LED: 5 flashes. Full explanation |
Source: Takagi 321923-000 troubleshooting guide, Table 2 (Error Codes). Code format is T-KJr2/T-K4 remote code, then the T-D2 code.
Detailed explanations
- Takagi tankless error codes 11 and 12: ignition failure and flame loss
- Takagi tankless error 99 and warning code 10: abnormal combustion
Sources
- Troubleshooting Guide 321923-000 (9/12/11): Non-Condensing On-Demand Water Heaters, T-KJr2, T-K4 and T-D2 (110, 310 and 510 models) (Takagi (A.O. Smith Water Products Company)) Covers: Takagi T-KJr2, T-K4 and T-D2 non-condensing tankless water heaters, indoor and outdoor. Other Takagi models have their own guides.