If you have a washing machine with a screen (LCD display) - electronic and lit error F15 or electromechanical Indesit machine (when there is no display) are lit "Delayed Washing" and "Extra Rinse" (when wringing) "Super Washing" and "Fast Washing
This is what error F15 looks like on a washing machine without a screen, when only the indicators are lit or flashing:

Contents
What does this error code f15 mean?
This error is only for washing machines with dryer! The heater is not in contact with the dryer relay.
Indesit error signals
Has not begun drying and displays an error, although the washing machine has already washed.
We check with our own hands.
- Hang the module of washing machine, disconnect from power for half an hour, so the machine will restart.
Replace and repair
- For washing machines with an electronic module, repair or replacement
- Replacement of the heating element after diagnosis.
- Repair the wiring and contacts between the washing machine module and the heating element.
Other washing machine errors:
- Error code F13: temperature sensor defective, drying doesn't work
- F14 error code: Heater burned out, need to be replaced