F9 on an LG range means the oven tried to heat but didn't reach the target temperature in the time it expects, so it flags a fault. The oven is telling you the heat isn't happening — the question is which part in the heat chain gave out. Here's the order a tech works it. (On a gas LG range this points at the igniter; on electric, the bake element.)
The most common cause of F9. On an electric oven the bake element burns out (often with a visible break or blister); on a gas oven the igniter weakens until it can't open the gas valve. Either way, no heat → F9.
Check it: On electric, look at the bake element at the bottom with the oven cool — a visible break or bubbling means it's done. On gas, watch if the igniter glows but the burner never lights. Both are a straightforward tech replacement.
The control board has a relay that switches power to the heating circuit. If that relay fails, the element/igniter never gets its signal even though the part itself is fine.
Check it: This is a tech diagnosis — if the element/igniter tests good but still no heat, the control relay is the suspect.
The oven sensor tells the control how hot it is. A failed sensor can make the control think the oven never heated (F9) even when it did, or shut heat off early.
Check it: A tech ohms the sensor against spec — an affordable part if it's out of range.
Repair — a bake element or igniter is an affordable, common part plus flat labor; the sensor is cheap; even a control relay is well below a new range. F9 rarely means the range is done.
In Middle Tennessee or the Baton Rouge area? We'll come to you, same-day. Anywhere else in the U.S.? Send a 10-second video, a real technician tells you exactly what's wrong for $50 (credited toward the repair), and we ship you the exact part. 24/7 — text, call, or upload anytime.
The oven isn't reaching temperature — a heating fault. On electric it's usually the bake element; on gas, the igniter; sometimes the control relay or oven sensor. It's a heat-chain problem, not a dead range.
You can inspect a visibly broken electric bake element or watch whether a gas igniter glows-but-won't-light, but the actual replacement (240V element or gas igniter) and any control/sensor work should go to a tech for safety. Your $50 Quick Check credits toward the repair.
Almost always — the parts (element, igniter, sensor) are affordable and the fix restores a working oven for a fraction of a replacement.