LG · Oven
LG Oven F9 Error Code
Oven failed to heat above 150°F in 5 minutes
What this error means
F9 triggers when the oven cannot exceed 150°F within five minutes of preheat with the door closed. LG shuts heat as a safety response—common on both gas and electric ranges but the failed part differs by fuel type.
How F9 is detected
When F9 appears on a LG oven, the control board has confirmed that water did not leave the machine within the programmed drain window. On LG LRG4113ST, LG LREL6325F, 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 F9 calls are resolved without parts: press clear/off, then turn the range breaker off five minutes. 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 F9 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
- Weak gas igniter glowing but not opening valve
- Open bake or broil element on electric models
- Temperature sensor reading ~1080Ω out of spec at room temp
- Failed relay on main oven control board
Step-by-step fixes
- 1Press CLEAR/OFF, then turn the range breaker OFF five minutes
- 2Retry Bake at 350°F and watch for igniter glow (gas) or element orange heat (electric)
- 3Confirm household gas valve is open on gas ranges
- 4Stop using the oven if F9 returns immediately after reset
When to call a technician
Schedule service for igniter, element, sensor, or relay board testing—F9 rarely clears without part replacement.
Affected models
- LG LRG4113ST
- LG LREL6325F
- LG LDG4313ST
Prevention & maintenance
- Clean drain filters and hose terminations monthly on high-use ovens to prevent F9 from lint and food debris buildup.
- Record when F9 appears in the cycle and whether it clears after a 60-second power reset on your LG oven—that detail speeds diagnosis if you call service.
- Keep the model and serial number from the rating plate when ordering parts for F9; LG uses multiple revisions with different harness lengths and board firmware.
- Photograph wiring connector orientation before disconnecting any component while troubleshooting F9; reversed plugs on pumps and valves cause immediate repeat faults.