Bosch Microwave Error Code E1

The E1 code on a Bosch microwave indicates a thermistor open circuit has been detected. The thermistor is the internal temperature sensor, and when its circuit reads as open, the control board cannot receive valid temperature data. The microwave responds by reverting to plug-in mode and displaying the E1 code for 3 seconds. The thermistor itself or its wiring will need to be inspected and tested to resolve the fault.

When the E1 error is active, the microwave reverts to a limited plug-in mode, meaning normal cooking functions are not available. Operating the microwave without a functioning thermistor removes an important layer of temperature monitoring and protection. It is best to avoid using the appliance for cooking until the thermistor fault has been diagnosed and corrected.

Repair costs vary depending on whether the issue is a failed thermistor, damaged wiring, or simply a loose connector. A replacement thermistor part typically ranges from around $15 to $60 depending on the model. If professional service is needed, labor costs can bring the total repair estimate to roughly $100 to $250. In some cases, a loose or corroded connector can be corrected without any parts cost at all.

A knowledgeable DIYer can inspect the thermistor wiring and connectors for obvious damage or loose connections, which may resolve the error without parts. However, working inside a microwave involves high-voltage components, including a capacitor that can retain a lethal charge even when unplugged, so the repair should only be attempted by those comfortable with proper high-voltage discharge procedures. If the thermistor component itself has failed, it will need to be replaced, which may require sourcing a compatible part.

Unplugging the microwave and plugging it back in may temporarily clear the displayed code, but the E1 fault will return if the underlying open circuit condition in the thermistor or its wiring has not been repaired. A reset does not fix the hardware fault, it only clears the stored error state momentarily. The thermistor circuit must be tested and the root cause corrected for the error to stop recurring.