Bosch · Oven
Bosch Oven F33 Error Code
Warming drawer sensor short circuit
What this error means
F33 indicates a short circuit in the warming drawer temperature sensor—the probe that monitors the drawer cavity sent abnormally low resistance, disabling warming drawer heat on models with a separate warming zone below the oven.
How F33 is detected
When F33 appears on a Bosch oven, the control board has confirmed that water did not leave the machine within the programmed drain window. On Bosch HBLP751UC, Bosch HBL8753UC, and similar variants, the drain pump runs for a fixed interval—often three to seven minutes on washers and dishwashers—while a pressure switch or turbidity sensor verifies the tub or sump is empty. If water remains, the cycle stops to prevent spin with a full tub or overflow on the next fill.
Most F33 calls are resolved without parts: turn off breaker and pull the warming drawer out fully. Restricted drain paths mimic pump failure because the impeller spins against a blocked hose or filter. Document whether the pump hums audibly during the drain step; a humming pump with no water movement points to a clogged filter or kinked hose, while silence may indicate a failed pump motor or loose wiring at the harness.
After clearing blockages, run a short cycle and listen at the drain hose for steady water flow. If F33 returns on the next load with a clean filter and straight hose, measure resistance at the pump motor connector per the service manual for your model before ordering a replacement pump assembly.
Common causes
- Drawer sensor wire crushed when the drawer was forced closed
- Spilled liquid shorting the drawer probe connector
- Failed RTD shorted to ground inside the drawer cavity
- Harness pinch between drawer slide and cabinet
Step-by-step fixes
- 1Turn off breaker and pull the warming drawer out fully
- 2Inspect the sensor entering the drawer rear wall and its harness along the slide
- 3Dry any moisture at the connector before reseat
- 4Test drawer sensor ohms per manual—should not read near zero
When to call a technician
Persistent F33 with dry, intact wiring requires warming drawer sensor replacement.
Affected models
- Bosch HBLP751UC
- Bosch HBL8753UC
- Bosch HBL8443UC
Prevention & maintenance
- Clean drain filters and hose terminations monthly on high-use ovens to prevent F33 from lint and food debris buildup.
- Record when F33 appears in the cycle and whether it clears after a 60-second power reset on your Bosch oven—that detail speeds diagnosis if you call service.
- Keep the model and serial number from the rating plate when ordering parts for F33; Bosch uses multiple revisions with different harness lengths and board firmware.
- Photograph wiring connector orientation before disconnecting any component while troubleshooting F33; reversed plugs on pumps and valves cause immediate repeat faults.