If you are experiencing the Navien Error Code 515-09, it means there is an abnormality with the PCB (printed circuit board) of your Navien water heater. This error code indicates a technical issue that needs to be addressed in order to restore the proper functioning of the unit.
To fix this error, the first step is to reset the unit by turning it off and on again. If the error persists, it is recommended to contact a professional technician or plumber who is familiar with Navien water heaters. They will be able to diagnose the issue with the PCB and take appropriate measures to resolve it.
It is important to address this error code as soon as possible to prevent any further damage to the water heater and ensure the continuous supply of hot water in your home. Ignoring the issue could lead to more serious problems and potentially higher repair costs in the future.