What F40 Means
F40 is unusually benign for an error code. Miele’s documentation records it as an impermissible state at the power electronics caused by the processor resetting after a power failure — and the remedy it gives is simply to switch the appliance off and on again.
Common Causes of F40
- Brief power failure or supply interruption while the machine was running
- Machine switched off at the wall part-way through a cycle
- Unstable supply on the circuit feeding the appliance
🔧 One Safe Check You Can Try
Do exactly what the documentation says: switch the machine off at its own switch, give it a few seconds, and switch it back on. If it starts normally and stays healthy, that is the end of it.
⚠ Why You Shouldn't Go Further Than That
- If the code keeps coming back without any power interruption to explain it, the supply or the board is to blame rather than a one-off reset, and that does need looking at.
- A built-in machine on a shared circuit with a kettle or a toaster can see dips that a dedicated supply would not, which is an installation question.
- Repeated resets during data writing are how stored settings get corrupted, which turns a harmless code into the more serious F41.
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
- F40
- 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.