Rheem Tankless Water Heater Code 45

Rheem Tankless Water Heater Code 45

Rheem Tankless Water Heater Code 45 indicates a water leak. This water heater has a water leak sensor at the bottom of the unit. When it senses water dripping or moisture, the unit will trip the sensor and throw an error code 45.  

How To Fix Rheem Tankless Water Heater Code 45?

Here is the step-by-step instruction you can follow to reset the error code 45:

  • Turn off your water heater at the circuit breaker.
  • Check the bottom of the water heater for dampness or moisture. Close the cold water valve so no more water can go to the water heater. 
  • Run a fan overnight to dry out the water that accumulates at the bottom of the unit. 
  • Once you notice no moisture at the bottom of your tankless water heater, turn on your tankless water heater.
  • Check the remote control display for the error code 45. If the error code persists, cycle the water heater off for a few minutes. Then, turn on the water heater again. I hope it will reset the fault code 45. 

How Do I Reset My Rheem Tankless?

Follow these simple steps to reset your Rheem Tankless Water Heater:

  • Turn off your water heater by unplugging the power cord. If you have an outdoor model, shut off the unit at the circuit breaker.
  • Leave the water heater for 30 seconds. It will give the unit enough time to detect and remove the glitch. 
  • 30 seconds later, restore the power to your tankless water heater. It should reset your water heater. 


Does A Rheem Hot Water Heater have a reset button?

Yes, Rheem Electric Hot Water Heater has a reset button. You can find the button at the upper thermostat. Unscrew the upper access panel, remove the insulation, and the reset button is on the upper thermostat. However, a tankless unit has no reset button. 

Why is my Rheem Tankless Water Heater not heating?

Your Rheem Tankless Water Heater won’t heat water due to one of the following reasons:

  • No gas is flowing to the burner
  • Improper gas pressure
  • Clogged burner
  • Defective igniter or flame sensor
  • Bad control or circuit board
  • Restricted flue

What are the codes for Rheem Water Heater?

Rheem Water Heater will display the following error codes:

  • Error code 5 means imperfect combustion alarm
  • Error code 1o means abnormal low rate combustion
  • Error code 11 indicates there is an issue with ignition
  • Error code 12 means flame failure. 

To get the complete list, read this article on Rheem Tankless Water Heater Error Codes


The water leak detected is what the error code 35 resembles on the Rheem Tankless Water Heater. You can reset this code by drying out the water from the bottom of the unit. Once you dry the dampness, cycle off the water heater. It should reset the error code 45. 

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