Miele Dishwasher Error Code F24

The F24 error code on a Miele dishwasher indicates a heater relay contact fault. Specifically, the control board detects 120VAC at the output of the heater relay 18 seconds after the drain sequence begins, at a point when the relay coil should be fully de-energized and the contacts should be open. The presence of line voltage on the heater circuit at this stage means the relay contacts have fused together, creating a permanent electrical connection that the control board cannot interrupt through normal switching commands.

The heater relay is a critical safety component responsible for controlling power delivery to the wash water heating element. Under normal operation, the relay opens its contacts during the drain cycle to cut power to the heater. When relay contacts weld or fuse, typically due to arcing caused by switching high current loads over time, the contacts physically bond together and can no longer open. This creates a condition where the heater could receive power at unintended times, which is both a functional fault and a potential safety concern.

The primary diagnostic action is replacement of the heater relay, as referenced in Section 004-4.8 of the technical documentation. A fused relay contact cannot be repaired by cleaning or resetting. The fault is a hardware failure internal to the relay itself. Because the control board is correctly detecting the unexpected voltage and generating the fault code, the board itself is typically not at fault. Technicians should confirm the relay is the source before replacing additional components.