Thermador Range Error Code F3

The F3 error code on a Thermador range indicates a fault with the oven temperature sensor, also called an RTD (resistance temperature detector). Specifically, the control board has detected either an open circuit or a short circuit condition from the sensor for a continuous period of 16 seconds or more. An open sensor means the electrical circuit through the sensor probe is broken, producing no readable resistance signal. A shorted sensor means the circuit is collapsed, often due to a pinched wire, producing a resistance reading that falls outside the expected range. Both conditions prevent the control board from accurately monitoring oven temperature, so the range locks out heating operations as a safety measure.

The oven temperature sensor is a probe mounted inside the oven cavity, typically at the rear wall, and it connects back to the ERC3 (Electronic Range Control) via a wiring harness. At room temperature, a properly functioning sensor should measure approximately 1000 ohms of resistance. Readings significantly above or below this value confirm a faulty sensor or wiring problem. Common causes of an open circuit include a broken probe element or a disconnected harness connector. Common causes of a short circuit include a wire pinched between oven components, damaged insulation from heat exposure, or physical damage to the sensor probe itself.

Diagnosing this fault requires checking all wiring connections at both the sensor and the control board, then measuring sensor resistance with a multimeter. If connections are secure and resistance is correct, the wiring harness should be traced for pinch points or insulation damage. If all external causes are ruled out and F3 persists, the ERC3 control board itself may be the source of the fault and will need replacement.