Miele Oven Error Code F198

Error code F198 on a Miele oven indicates an open circuit condition in the cooling-air temperature sensor, designated R30-34. This sensor is a Pt1000-type resistive temperature detector, meaning it uses a platinum element with a nominal resistance of 1000 ohms at 0 degrees Celsius. Its resistance rises predictably with temperature, allowing the oven's control system to monitor the temperature of the cooling airflow that protects internal electronics and cavity components. When the control board detects that the circuit is open rather than reading an expected resistance value, it logs F198 and typically halts or limits operation to prevent overheating damage.

The open circuit condition means the electrical path through the sensor has been broken entirely. This can result from a failed sensor element, a broken wire in the sensor harness, or a corroded or disconnected connector between the sensor and the control board. Pt1000 sensors can crack or fail internally after prolonged thermal cycling, and the wiring routed near heat sources inside the oven cavity is also susceptible to insulation degradation and wire fracture over time.

Because the cooling-air sensor protects critical internal components from heat damage, this fault should not be ignored or bypassed. The prescribed first diagnostic step is direct replacement of the R30-34 sensor as detailed in Section 030-4.8 of the service documentation. Before replacing the sensor, a technician should inspect the harness and connectors for visible damage or looseness, as a wiring fault can mimic a failed sensor and would require a different repair approach.