311
Takagi
Outlet Thermistor Failure (Open or Short)
Takagi water heater displays error 311 and will not fire.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Failed outlet thermistor sensor, Damaged thermistor wiring harness, Corroded connector at PCB, Water intrusion at sensor connection
How to Fix / Troubleshooting
Safety first: Turn OFF power and gas. Allow the unit to cool before touching any internal components.
Steps:
- 1. Locate outlet thermistor: The outlet thermistor is typically mounted on the hot water outlet pipe or heat exchanger outlet. Refer to the service diagram for your specific Takagi model.
- 2. Inspect wiring: Check the thermistor’s wiring harness for cuts, burns, or pinched sections. Ensure the connector at the PCB is fully seated and free of corrosion.
- 3. Check for moisture: Look for signs of water leaks around the outlet area that may have dripped onto the sensor or connector. Repair any leaks before replacing parts.
- 4. Replace thermistor if needed: If wiring looks good, replace the outlet thermistor with a genuine Takagi part. Disconnect the old sensor, remove it from the pipe or bracket, install the new one, and reconnect the harness.
- 5. Reset and test: Restore power and gas, clear the error, and run hot water to confirm normal operation.
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Repair Difficulty
Medium
3/5
Required Part
Outlet Thermistor
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