Effects
The "F5" error means that the temperature sensor has recorded an unusual reading while using hot water. This usually is a sensor error rather than a malfunction of your hot water heater.
Identification
Along with the "F5" error, codes like "F6," "F23" and "F24" also have to do with the temperature sensor. Look for these errors that may appear at the same time as the "F5" error.
Prevention/Solution
Check the temperature sensor connection. The sensor may be moved out of place or disconnected. Remove it from the plug and plug it back in to reset the connection. If the error appears again, replace the sensor on the washer. Use a website like Appliance Parts Pro to search for your model number and find the right part.