The data is on the type plate, which you can find as shown.
Error code F42 indicates that the mains frequency detection is missing or is not being detected correctly.

Miele
F42

42

Error code F42 is what is known as an “electronics fault”. That means – the electronics in your machine are very likely defective. With a repair or with refurbished electronics from us, the error is fixed for good and will not come back.
Please enter the model number of your appliance in the corresponding field and find the right products to fix your error.
The data is on the type plate, which you can find as shown.
No problem. Send us the most important details about your appliance and the fault. Our team will review your information and help you find the right solution.