Warning: Your Navien boiler has detected a potential issue with the return water temperature sensor. It's safe to continue using other appliances, but this issue requires professional attention.
How to Fix Navien Code E736
Check if your boiler is still heating your home. If it is, you can continue using it until a professional can repair it.
Turn off your boiler if it's not heating your home or if you're not comfortable using it.
Contact a licensed HVAC technician to diagnose and repair the issue. Do not attempt to repair this yourself.
How to Reset Navien Code E736
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.
What does E736 mean?
The E736 error on your Navien boiler indicates a failure in the return water temperature thermistor. This sensor measures the temperature of the water returning from your heating system. If it's not working correctly, your boiler can't accurately control the water temperature, leading to inefficient heating and potential system damage. This error is typically caused by a faulty thermistor, but it could also be due to a wiring issue or a problem with the boiler's control board.