Your safety is our #1 priority. Contact Happy Plumbing for further troubleshooting. Our technicians can help you diagnose the problem.
Please note: Your water heater model may use different codes or may provide error codes that are not given here. Therefore you’ll want to consult the manual for your specific heater.
| ERROR CODE | MEANING | TAKAGI MODELS |
|---|---|---|
| TAKAGI ERROR CODE 1 | Wrong dip switch setting Red LED / Computer Board Fault | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 2 | Inlet Thermistor / Output Thermistor / Air-fuel ratio rod failure | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 3 | Ignition Failure / Flame Loss | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 4 | Abnormal Fan Motor | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 5 | Warning for 991 error code / Abnormal Combustion | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 6 | Abnormal Gas Valves / Abnormal Solenoid Gas Valve / False Flame Detection | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 03 | Wrong dip switch setting, 110 (T‐ KJr2), 310 (T‐K4) Remote | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 10 | Warning for 991 Error Code | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 11 | Ignition failure | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 12 | Flame loss | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 31 | Output Thermistor | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 32 | Inlet Thermistor | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 39 | Air-Fuel Ratio Rod Failure | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 51 | Abnormal Gas Valves | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 55 | Abnormal Solenoid Gas Valve | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 61 | Abnormal Fan Motor | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 70 | Computer board fault | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 72 | False flame detection | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 74 | Remote controller communication failure | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 99 | Abnormal combustion | 110 (T‐ KJr2), 310 (T‐K4) Remote |
| TAKAGI ERROR CODE 31 | Wrong dip switch setting, possibly LP gas set when the fuel is Natural gas or vice versa | T-D2, T-H2-OS T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS T-M32, T-M50 |
| TAKAGI ERROR CODE 70 | Computer board failure – see 701 | |
| TAKAGI ERROR CODE 72 | False flame detected – see 721 | |
| TAKAGI ERROR CODE 74 | Remote control problem – see 741, 751 | |
| TAKAGI ERROR CODE 099 | Improper combustion – see 991 Watch out: this is an unsafe condition risking CO hazards. | |
| TAKAGI ERROR CODE 101 | Improper combustion. Watch out: this is an unsafe condition. Look for a blocked flue or chimney (or downdrafts in the chimney) or a problem with the draft inducer fan. Warning for 991 error code | T-D2, T-H2-OS T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS T-M32, T-M50 |
| TAKAGI ERROR CODE 111 | Ignition failure; the burners do not light. Check for a bad igniter, flame sensor, gas valve. Check for gas supply. Check for a blown fuse on the circuit board. | T-D2, T-H2-OS, T-M32, T-M50 |
| TAKAGI ERROR CODE 121 | Burner flame lost. See code 111 above. | T-D2, T-H2-OS, T-M32, T-M50 |
| TAKAGI ERROR CODE 311 | Output thermistor failure. Check the thermistor and its wires on the heat exchanger. Replace the thermistor if you don’t see a loose or disconnected wire. | T-H2-OS T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS T-M32, T-M50 |
| TAKAGI ERROR CODE 321 | Input / Inlet thermistor failure. Check the thermistor and its wires at the water inlet. Replace the thermistor if you don’t see a loose or disconnected wire. | T-H2-OS T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS T-M32, T-M50 |
| TAKAGI ERROR CODE 331 | Mixing Thermistor failure | T-H2-OS T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS T-M32, T-M50 |
| TAKAGI ERROR CODE 341 | Thermistor failure | T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS |
| TAKAGI ERROR CODE 391 | Air-fuel ratio rod failure. Check wire connections and if no loose wire, replace the AFR rod. | T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS T-D2, T-M32, T-M50 |
| TAKAGI ERROR CODE 441 | Flow Sensor Failure (Easy-Link or Multi-Link System Only) Possible: Inlet filter clogged, water flow problem. Also, check for loose wire connections. | T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS T-D2, T-M32, T-M50 |
| TAKAGI ERROR CODE 510 | Gas valve failure. Inadequate gas pressure or flow. | T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS T-D2, T-M32, T-M50 |
| TAKAGI ERROR CODE 551 | Gas solenoid valve failure. Check the gas supply and if no problem the solenoid needs replacement. | T-H2-OS, T-M32, T-M50 |
| TAKAGI ERROR CODE 611 | Abnormal fan motor | T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS T-D2, T-M32, T-M50 |
| TAKAGI ERROR CODE 621 | Exhaust fan motor (indoor models only) | T-H2-OS |
| TAKAGI ERROR CODE 631 | Pump Failure | T-H2-OS, T-M32, T-M50 |
| TAKAGI ERROR CODE 651 | Flow Adjustment Valve Fault (Easy-Link or Multi-Link System only) | T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS T-D2, T-M32, T-M50 |
| TAKAGI ERROR CODE 661 | Bypass valve fault (540 (T-H3) model only) | T-H2-OS, T-M32, T-M50 |
| TAKAGI ERROR CODE 681 | External fan motor failure | T-M50 |
| TAKAGI ERROR CODE 701 | Computer board failure; check for loose wires, electrical power supply, and signs of damage to the board such as black or brown marks indicating overheating or burned | T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS T-D2, T-M32, T-M50 |
| TAKAGI ERROR CODE 711 | High Limit Switch / Overheat Cutoff Fuse Circuit is Compromised Watch out: this is an unsafe condition. | T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS |
| TAKAGI ERROR CODE 721 | False flame detected. Check for condensate accumulation, blocked or missing condensate drain, and condensate leaks. | T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS T-D2, T-M32, T-M50 |
| TAKAGI ERROR CODE 741 | Remote control not communicating with the water heater, check remote batteries, check remote sensor wiring, and remote control access line of sight. | T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS T-M32, T-M50 |
| TAKAGI ERROR CODE 751 | Temperature Controller Problem | T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS |
| TAKAGI ERROR CODE 761 | Communication Error in Easy-Link or Multi-Link System. | T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS T-D2, T-M32, T-M50 |
| TAKAGI ERROR CODE 941 | Abnormal exhaust temperature Watch out: this is an unsafe condition risking CO hazards. | T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS |
| TAKAGI ERROR CODE 991 | Improper gas combustion. Abnormal combustion. Watch out: this is an unsafe condition risking CO hazards. If this indicator is on from the first activation of the heater it may not be properly adjusted for the elevation at which the heater is installed. Check for blocked exhaust flue or under-sized exhaust flue. Check for debris clogging the gas burner or for a failed or blocked fan. | T-H2-OS, T-H3-DV/OS, T-H3J-DV/OS, T-H3S-DV/OS T-D2, T-M32, T-M50 |