What F42 Means
F42 means the machine could not read the mains frequency: Miele’s documentation describes no or too few voltage zero-crossings counted in a six-second window. On the CM6 platform the documented cause is a defective power electronics board, and the remedy is to replace it.
Common Causes of F42
- Power electronics unable to detect the supply waveform
- Supply itself unstable or non-sinusoidal, for example from an inverter
- Poor connection at the appliance supply
🔧 One Safe Check You Can Try
Check what else is on the socket. A built-in coffee machine sharing an extension or a multi-way adaptor with other kitchen loads gets a messier supply than one on its own outlet, and that context is worth reporting.
⚠ Why You Shouldn't Go Further Than That
- Miele names the power electronics as the cause on this platform, and that board is model-specific and requires setup after fitting.
- If the supply rather than the board is to blame, a new board fails the same way — and confirming which needs the supply measured.
- The board is inside a built-in appliance that has to come out of its housing on runners before anything can be reached.
Opening a panel to inspect or repair something yourself doesn't automatically cancel your manufacturer's warranty — but it can risk accidental damage, and some manufacturers do have specific service conditions. Check your product's warranty terms, or ask us, before deciding.
Technical Reference
- Code
- F42
- Appliance
- Miele coffee machine
- Maker documentation
- Miele owner manuals and use & care guides
- Checked
- September 2026
Code meanings can change between control generations. Before acting on a code, match the full model number on your appliance's rating label against the manual for that model. We are an independent repair service, not affiliated with Miele & Cie. KG.