Bosch Range Error Code F33

The F33 error code on a Bosch range indicates a warming drawer temperature sensor failure in the open circuit condition while the warming drawer is actively in use. An open sensor fault means the control board is receiving no valid resistance signal from the warming drawer's temperature sensor, which is typically a negative temperature coefficient (NTC) thermistor. The control board interprets an open circuit as the sensor wire being broken, the sensor itself failing, or a connector losing contact somewhere along the circuit path.

Bosch engineers built a 20-second fault delay into the F33 detection logic specifically to prevent false error triggers. Warming drawer sensor wires tend to be longer than other oven sensor wires because of the drawer's physical location lower in the range chassis, and longer wire runs are more susceptible to picking up electrical line noise. The 20-second window ensures the control board only flags F33 when the open circuit condition is persistent rather than a momentary signal dropout caused by interference.

When F33 appears, the warming drawer circuit is the primary area to inspect. The failure can originate at the sensor element itself, at any connector or terminal block along the sensor wire harness, or at the control board input where the sensor signal is read. Physical damage to the wiring from heat exposure or sharp chassis edges is also a recognized cause given the routing path through the lower cabinet area.