Bosch · Oven
Bosch Oven F43 Error Code
Upper latch motor or wiring fault
What this error means
F43 indicates the upper or single oven latch motor or its wiring failed during a lock command—Bosch service literature groups F43 with jammed switches, pinched common wires, and defective latch motors on the power board P24 circuit.
How F43 is detected
When F43 appears on a Bosch oven, the control board has confirmed that water did not leave the machine within the programmed drain window. On Bosch HBL8753UC, Bosch HBL8454UC, 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 F43 calls are resolved without parts: turn off breaker and inspect latch wiring visible at the door hinge pass-through. 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 F43 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
- Latch motor wire pinched between oven frame and chassis
- Common wire shorted to ground on the latch harness
- Broken solder joint in P24 header on the power board
- Latch motor windings failed open
Step-by-step fixes
- 1Turn off breaker and inspect latch wiring visible at the door hinge pass-through
- 2Verify latch switches click manually when the hook engages—do not bypass switches
- 3Reseat P24 and P10 connectors from the rear service access
- 4Do not run self-clean until latch confirms lock audibly
When to call a technician
F43 after connector reseat requires latch motor assembly or power board replacement.
Affected models
- Bosch HBL8753UC
- Bosch HBL8454UC
- Bosch HBLP751UC
Prevention & maintenance
- Clean drain filters and hose terminations monthly on high-use ovens to prevent F43 from lint and food debris buildup.
- Record when F43 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 F43; Bosch uses multiple revisions with different harness lengths and board firmware.
- Photograph wiring connector orientation before disconnecting any component while troubleshooting F43; reversed plugs on pumps and valves cause immediate repeat faults.