Bosch Refrigerator Error Code F21

F21 indicates that the temperature sensor in the cool-fresh compartment has an open circuit, meaning the signal between the sensor and the electronics module has been completely interrupted. The refrigerator cannot read the temperature in that compartment and will display this code until the fault is corrected. The issue typically points to a failed sensor, a broken wire, or a disconnected connector in the sensor circuit.

The cool-fresh compartment temperature may become unreliable when the F21 error is active because the control system cannot receive sensor feedback for that zone. Standard refrigerator and freezer compartments may continue operating normally if their sensors are unaffected. It is best to resolve the fault promptly and monitor compartment temperatures with a standalone thermometer in the meantime.

If only the sensor needs replacement, parts and labor typically range from around 75 to 200 dollars depending on the service provider and part pricing. Wiring harness repairs can vary widely based on how accessible the damaged section is. If the electronics module is at fault, costs can rise significantly, often falling in the range of 200 to 500 dollars or more for parts and professional installation.

Checking for a disconnected or loose connector is a straightforward task that many homeowners can perform safely with the refrigerator unplugged. Testing the sensor and wiring harness for continuity requires a basic multimeter and some comfort with electrical diagnostics. Replacing the sensor or harness is also manageable for experienced DIYers, but if the fault traces back to the electronics module, professional service is recommended.

A power reset by unplugging the unit for a few minutes may temporarily clear the displayed code, but the error will return if the underlying open circuit condition still exists. The F21 fault is hardware-based and requires the sensor, wiring, or connector issue to be physically corrected before the code will stay clear. A reset is useful for confirming whether the fault is intermittent, but it is not a repair.