Bosch Range Error Code E104

The E104 error code on a Bosch range indicates that the Cavity 1 temperature sensor has shorted to ground. The temperature sensor, also called a thermistor or RTD probe, is responsible for continuously monitoring the oven cavity temperature and reporting that data back to the control module. When the sensor or its wiring develops a short circuit to ground, the control module receives an out-of-range signal that falls outside normal operating parameters, triggering E104. As a protective response, the control module immediately halts all heating functions in Cavity 1 and forces the cooling fan to run at high speed to dissipate any residual heat.

The most common root cause is a wiring fault rather than sensor failure itself. The sensor wires run through areas of the range that experience significant heat cycling, vibration, and mechanical stress over time. This can cause wire insulation to degrade, crack, or become pinched against metal components, creating a direct short to the chassis ground. Connectors at the sensor or control module can also develop corrosion or loose terminals that cause intermittent or permanent short conditions. A thorough visual inspection of the entire sensor wiring harness, from the probe at the oven cavity wall to the control board connector, is the required first step.

If the wiring and connectors check out visually, the next step is to measure the resistance of the temperature sensor directly at its terminals. A properly functioning sensor will show a specific resistance value that corresponds to ambient temperature. A shorted sensor will typically show near-zero ohms or continuity to ground. If the sensor resistance reads within the expected range and no wiring faults are found, the control module itself may be misreading the signal or generating a false fault, making it a candidate for replacement.