Takagi Error Code 101: Combustion Abnormality
How to Fix Takagi Code 101
- Step 1: Ensure all gas appliances are working correctly. If other gas appliances aren't working, there may be a gas supply problem.
- Step 2: Check the venting for any obvious obstructions like leaves, snow, or debris. Clear any blockages you can safely reach from the ground.
- Step 3: Contact a qualified HVAC technician or plumber to inspect the unit and diagnose the problem. Do not attempt to repair the unit yourself.
How to Reset Takagi Code 101
- 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.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Takagi Error Code 101 Mean?
The Takagi error code 101, 'Combustion Abnormality,' means the unit's control board isn't seeing the expected flame signal during operation. This can happen for a few reasons, but it always points to a problem in the burner or venting system. The unit is designed to shut down as a safety measure when this happens to prevent the uncontrolled release of gas or the production of dangerous levels of carbon monoxide. When this error occurs, the water heater will likely lock out, meaning it won't attempt to restart until the issue is resolved and the error is cleared. Continuing to try and run the unit without addressing the underlying problem is unsafe. A qualified technician needs to diagnose the root cause and make the necessary repairs to ensure safe and reliable operation.
Common Causes
- Blocked or restricted venting, preventing proper exhaust of combustion gases.
- Insufficient gas supply to the unit, leading to incomplete combustion.
- Faulty flame rod or igniter, preventing proper flame detection or ignition.
- Condensate buildup in the venting or combustion chamber.
- Malfunctioning gas valve, not providing the correct gas flow.
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Venting appears obstructed | Manually inspect the vent run for blockages, crushed sections, or improper slope. | Clear vent path with proper slope per installation manual. |
| Gas pressure suspected to be low | Measure the incoming gas pressure at the unit's gas valve with a manometer. | Gas pressure within the range specified on the unit's nameplate (typically 4-7" WC for natural gas). |
| Flame rod signal is weak or absent | Measure the flame rectification signal (DC microamps) at the control board while the unit is firing. | Flame signal within the range specified in the service manual (typically 2-10 uA DC). |
| Igniter fails to spark | Visually inspect the igniter for cracks or damage. Use a multimeter to check for continuity. | Intact igniter with continuity. |
Applicable Takagi Models
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Flame Rod | — | — | — |
| Gas Valve | — | — | — |
| Igniter | — | — | — |
Related Codes on Same Models
Other codes that affect the same Takagi model families as 101.
| Code | Description | Severity |
|---|---|---|
| 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 |
| 321 | Inlet Temp Sensor | Warning |
| 391 | Exhaust Temp Sensor | Warning |
| 510 | Gas Solenoid Valve | Critical |
| 610 | Fan Motor Fault | Warning |