Miele Dishwasher Error Code F42

F42 is a line frequency registration fault, meaning the dishwasher's control electronics cannot confirm that the incoming AC power frequency falls within the expected 50 Hz or 60 Hz range (each with a plus or minus 5 Hz tolerance). The dishwasher stops operating as a protective measure. The fault points to a problem with the power supply feeding the appliance rather than a mechanical failure inside the unit.

No, you should not attempt to operate the dishwasher while the F42 fault is active. The error indicates that the control system cannot confirm the power supply is within safe operating parameters. Running the appliance under these conditions risks damage to the motor, pump, and control electronics.

If the issue is with the home's electrical supply or circuit, electrician fees typically range from $75 to $250 or more depending on the work required. If the control board itself needs replacement, repair costs including parts and labor generally range from $200 to $500 or higher, depending on the specific model and local labor rates.

The first step requires a qualified electrician or appliance specialist to inspect your home's power supply and dedicated circuit, so this is not a typical DIY repair. If the power supply is confirmed to be normal and the fault continues, a technician will need to evaluate the control board. Do not attempt to bypass or ignore this fault, as running the appliance on abnormal power can cause further damage.

A simple power reset is unlikely to permanently clear F42 if the underlying power supply issue has not been resolved. The fault will typically return as soon as the control board again fails to detect a valid frequency on startup. The root cause, whether a supply problem or a faulty control board, must be addressed first.