Takagi Error Code 111: Ignition Failure

Severity
Critical
Type
digital display
Estimated repair cost: $100 — $250 (parts + labor)
Warning: This error indicates a failure to ignite the gas. Shut down the unit immediately and do not attempt to restart it, as this could create a dangerous accumulation of gas.

How to Fix Takagi Code 111

  1. Step 1: Ensure the main gas supply valve to the water heater is fully open.
  2. Step 2: Check other gas appliances in your home to see if they are working. If not, there may be a broader gas supply issue.
  3. Step 3: Visually inspect the vent for any obvious obstructions (leaves, snow, debris). Do not attempt to disassemble the vent.
  4. Step 4: If the gas supply is confirmed and the vent appears clear, contact a qualified HVAC technician to diagnose and repair the unit.

How to Reset Takagi Code 111

  1. Turn off the unit using the power button on the front panel.
  2. Turn off the gas supply valve.
  3. Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
  4. Restore power at the breaker, then open the gas valve.
  5. 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 111 Mean?

Error code 111 on your Takagi tankless water heater signifies an ignition failure. This means the unit tried to start the burner but failed to detect a flame. Several things could cause this, but the most important thing is safety. Because unburned gas may be present, it's vital to address this issue promptly. The system locks out as a safety measure to prevent a dangerous buildup of gas. When the unit calls for hot water, the control board starts the fan, opens the gas valve, and sends a spark to the igniter. The flame sensor then verifies that a flame is present. If the flame sensor doesn't detect a flame within a specific timeframe, the unit shuts down and displays the 111 error code. This could be due to a problem with the gas supply, the igniter, the flame sensor, or the control board itself. Because this involves gas, it's best to leave diagnosis and repair to a qualified technician.

Common Causes

  • Gas supply interruption (main gas valve closed, low gas pressure)
  • Faulty igniter (not producing a spark)
  • Defective flame sensor (not detecting the flame)
  • Blocked or restricted vent (insufficient air for combustion)
  • Malfunctioning gas valve (not opening to allow gas flow)
  • Failed control board

Diagnostic Steps

If... Check Expected
Unit displays error 111 Verify gas supply pressure at the unit's gas valve test port Within the manufacturer's specified range (typically 4-7" WC for natural gas, 8-11" WC for propane)
Gas pressure is within range Inspect the igniter for visible damage and test for spark during ignition attempt Audible and visible spark at the burner
No spark is present Measure the igniter's resistance Resistance within manufacturer's specifications (refer to service manual)
Spark is present Measure the flame sensor's microamp signal during operation 2-10 microamps DC (typical range, refer to service manual)

Applicable Takagi Models

Replacement Parts

Part OEM Number Est. Cost Where to Buy
Igniter T-IC-001 — Find Part
Flame Sensor T-FS-001 — Find Part
Gas Valve — — —

Related Codes on Same Models

Other codes that affect the same Takagi model families as 111.

Code Description Severity
101 Combustion Abnormality 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