F21…on a WAE i’m guessing….is either to do with motor action or faulty Control module.
Its something concerned with electrical spikes if i remember correctly.
Soemtimes there’s nothing wrong with the motor which then means a new board….and you will need to enter the test programme to probably clear the inital fault if you want to further test it.
Of course , if its not a WAE then you can ignore the rest 🙂