Gas, electric, one cavity or two: that answer picks the part behind an LG oven F9 error, because the code itself only says the oven heated too slowly. Find your branch, run the owner checks, then see what each repair costs.
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An LG oven F9 error means the oven did not heat fast enough during preheat. LG Canada’s electric-range page sets the line at 150°F after five minutes. LG’s US code list words it as “upper oven is not heating properly.” The code names a symptom; the branches below name the part.
F9 and F-9 are the same code; LG’s own help pages print it both ways. The display shows it on freestanding and slide-in LG ranges, gas and electric, and on two-cavity models where the upper oven failed its warm-up. Press Clear/Off and the beeping stops; the fault stays.
The board does not know which part is weak. It knows the temperature sensor reported too little heat in the time allowed. So the useful question is which heat source your oven has, and that is how this page is organized. Spark sees this code on LG appliance calls in San Diego County; the tests below are the ones we run.
Find your oven on the left, then read across: the warm-up it should pass, LG’s note, our test.
| Display / LG platform | What should happen in five minutes | What LG says about F9 | What Spark measures |
|---|---|---|---|
| F-9 / F9 — LG electric range (single oven, e.g. LSE series) | Hidden or visible bake element glows; the cavity passes 150°F. | LG Canada: failed to heat to 150°F after five minutes; element, relay PCB, relay connector or an electrical fault. | Element continuity, voltage at the terminals with the relay closed, connector heat damage. |
| F9 — LG gas range (LRG / LDG type) | Igniter glows red, then the burner lights within 30 to 60 seconds. | Check the main and oven gas shut-off valves; cut power five minutes; repeat code = service. | Igniter current draw, voltage at the safety valve, gas supply pressure. |
| F9 — LG double-oven range (upper cavity) | The small upper oven reaches temperature on its own element or burner. | “Upper oven is not heating properly.” Lower-oven faults carry other codes. | Upper heat source and upper sensor, read separately from the lower oven. |
| F9 — LG wall oven or ProBake convection model | The cavity reaches its set bake temperature; on Convect, the rear fan runs. | No published F9 wording for wall ovens; check the model manual. | Sensor, bake element, convection element and fan, relay board last. |
No panels off and no meter. Each fork sends you down one branch or rules it out; stop at the first one that fails and note what you saw.
Write down the exact code and the cavity it belongs to. F1, F2 or F16 beside F9 → sensor branch. F9 alone → go to the gas or electric fork.
Confirm the shut-off valve behind the range is open. Start Bake and look through the window at the bottom burner: red glow, then flame inside about a minute. Glow with no flame → igniter or valve branch.
On an exposed bake element, a dull orange glow should appear within a couple of minutes. No glow, a blister or a split → element branch. A hidden element under the floor cannot be seen → go to the warm-up test.
Set Bake to 350°F and keep the door shut. After ten minutes the oven should feel clearly hot when opened. LG warns store thermometers are not accurate, so use one only to see whether heat arrived → little heat = relay or sensor branch.
Press Clear/Off, then switch off the range breaker. LG’s US list says 30 seconds, LG Canada says 3 to 5 minutes and the gas manual says five, so five covers all three → F9 back on the next bake = a part.
Each line is a row from our oven repair price table, parts and labor in one figure. The $90 visit is not added on top: it is the first $90 of the row you approve.
| Branch and reading | What we replace | Parts + labor |
|---|---|---|
| Gas: igniter glows, current draw below what the valve needs | Hot-surface igniter, then a timed light-off test. | $220 – $380 |
| Electric: no continuity across the element, or a split sheath | Bake or broil element, terminals cleaned or replaced. | $220 – $320 |
| Any oven: sensor reading drifts from the cavity, or F9 rides with F1/F2 | Oven temperature sensor (thermistor) and its rear connector. | $180 – $280 |
| Electric: element good, relay closes, no voltage at the terminals | Electronic control board or relay board, after the harness checks good. | $380 – $520 |
| F10 / F20 beside F9 after a self-clean: lock motor stuck or its switch open | Door latch or self-clean lock motor. | $180 – $280 |
| Convection model: bake heat present, fan stalled or slow | Convection fan motor. | $280 – $420 |
A burnt connector behind the back panel is usually repaired at the visit. Range prices by type: range repair.
Each branch ends at one measurement:
A gas igniter can glow and still be too weak to open the valve. A clamp meter on the igniter circuit shows the current it draws, which tells a tired igniter from a valve that never opens.
On electric LG ranges the bake relay can click and still pass no power. We read voltage at the element terminals with the relay closed, so a board is never replaced for a dead element, or the reverse.
After a gas oven repair the fittings at the valve get a leak check while the back is still open. Spark is registered with the California Bureau of Household Goods and Services, #C 62399, and insured.
Any line below ends the owner part of the tree. Switch the oven off and call.
LG’s US code list, one line each, with the first thing to do.
| Code | LG’s meaning | First move |
|---|---|---|
| F1 / F2 | Upper oven thermistor error. | Clear/Off, breaker reset; repeat = sensor or its wiring. |
| F4 / F5 | Lower oven thermistor error. | Same reset; the lower sensor is tested on its own. |
| F3 | Touch pad sensor key error. | Breaker reset only; a stuck key pad is a panel repair. |
| F6 | Upper oven heating error. | A cousin of F9; same heat-source tests. |
| F7 / F17 | Convection fan error. | Listen for the rear fan on Convect Bake; silent = fan motor. |
| F10 / F20 | Door locking system failure, upper / lower oven. | Clear/Off; repeat after self-clean = lock motor. |
| F11 | Communication error. | Breaker reset; a repeat F11 is a board-to-board link we trace. |
| F16 / F19 | Oven sensor issue / oven heating error. | Treated like F9: sensor first, then heat source. |
| PF | Power was interrupted. | Not a fault: Clear/Off and reset the clock. |
Oven symptoms without a code are on signs your oven needs repair; stovetop burner faults are on stove repair. A drain code on an LG washer? See LG washer OE code.
Searches for this code peak in December and July; book early in those months. Calls placed before noon are usually seen same-day by a technician out of Spring Valley.
Every part we fit is covered by a 90-day parts and labor warranty. For other LG appliances, see LG appliance repair in San Diego; for any oven brand, oven repair and the repair cost guide.
$90 service call
First $90 of the repair · 90-day parts and labor · before-noon calls seen same-day
📞 Call (619) 330-5105📅 Book an AppointmentA code that survives five minutes without power is not a setting. Book the visit; the branch is confirmed with a meter on the first stop, and the repair is quoted before anything is replaced.
The oven failed its warm-up check. LG Canada’s electric-range page says the cavity did not reach 150 degrees F after five minutes of preheat. LG’s US code list reads “upper oven is not heating properly.”
The beep is the alarm that comes with every LG function code. Press Clear/Off to silence it. Then cut power at the breaker for five minutes; if F9 comes back on the next bake, a part has failed.
Press Clear/Off, switch the range breaker off, wait, and switch it back on. LG’s US list gives 30 seconds, LG Canada 3 to 5 minutes, and the gas manual five minutes, so five minutes is the safe choice. On a gas range, confirm the gas shut-off valve is open first.
On most LG ranges it is a slim metal probe held by two screws on the back wall inside the oven cavity. Its plug sits behind the wiring cover on the back of the range, so testing it means pulling the range out.
Often. LG says the igniter glows red and lights the burner in about 30 to 60 seconds. A glow with no flame points to a weak igniter or the gas valve; we measure the igniter current to tell which.
You can reset it, open the gas valve and watch the igniter or element. Naming the part takes current and voltage readings on live gas and 240-volt circuits.
It depends on the branch: an igniter runs $220 to $380, a bake element $220 to $320, a temperature sensor $180 to $280, and a control board $380 to $520. The service call is credited to whichever you approve.
On a double-oven range, LG’s list ties F9 to the upper oven; lower-oven faults use other numbers. For a wall oven, check the model’s own manual; we test the bake element, sensor and board the same way.
Not directly. LG lists F11 as a communication error between control parts, not a heating fault. Reset the breaker once; a repeat F11 needs the board link traced.
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