Takagi Error Code 200: Overheating

Severity
Warning
Type
digital display
Estimated repair cost: $75 — $200 (parts + labor)
Warning: The water heater has shut down due to overheating. You likely have no hot water. Resetting *might* restore function, but the underlying problem needs diagnosis.

How to Fix Takagi Code 200

  1. Step 1: Check that all hot water taps are fully closed. A small drip can trigger the heater unnecessarily.
  2. Step 2: Ensure the water supply valve to the unit is fully open.
  3. Step 3: Press the reset button on the unit. If the error reappears shortly after, call a qualified technician.

How to Reset Takagi Code 200

  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 200 Mean?

The Takagi error code 200 indicates the unit's high limit switch has tripped, meaning the water temperature exceeded its maximum safety threshold. This shuts down the burner to prevent damage and potential scalding. Several things can cause this, but it usually points to a problem with water flow, burner operation, or a faulty sensor. The unit is designed to protect itself, so it's important to figure out why it's overheating instead of repeatedly resetting it. When this happens, the heater stops producing hot water, and you'll see the 200 error code displayed. The unit will likely lock out and require a manual reset. While a temporary reset might restore hot water, the underlying issue will likely cause the problem to reoccur. Ignoring this error can lead to further damage to the unit or even create a safety hazard.

Common Causes

  • Scale buildup inside the heat exchanger restricting water flow.
  • Insufficient water flow rate through the unit.
  • Faulty high limit switch or thermistor.
  • Combustion issues causing excessive burner temperature.
  • Blocked or restricted venting.

Diagnostic Steps

If... Check Expected
Unit displays error 200 Measure inlet water flow rate Within specified range (e.g., 0.5-10 GPM depending on model)
Flow rate is within range Inspect heat exchanger for scale buildup using a borescope Minimal to no scale
No visible scale Check the resistance of the high limit switch at room temperature Continuity (closed circuit)
High limit switch has continuity Measure the voltage to the gas valve during operation Appropriate voltage (e.g., 24V DC)

Applicable Takagi Models

Replacement Parts

Part OEM Number Est. Cost Where to Buy
High Limit Switch TK5000500 — Find Part
Flow Sensor TK5000300 — Find Part
Thermistor — — —

Related Codes on Same Models

Other codes that affect the same Takagi model families as 200.

Code Description Severity
101 Combustion Abnormality Critical
111 Ignition Failure Critical
121 Flame Failure Critical
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