Michael Thompson Key Takeaways
- F5 means the oven control board has detected a relay failure, and a reset cannot repair burned or welded contacts.
- Do not use the oven with F5: a welded relay can keep an element on with nothing regulating the temperature.
- A shorted element can overload the relays, so test the element before approving a new board.
- This site puts LG ranges at 13 to 18 years of life, so a younger oven with a single board fault is worth repairing.
- Only board failures on ovens past about 12 years, with other wear, call for serious replacement consideration.
The Bottom Line
Repair an F5 on an oven under about 13 years old once the element is cleared, and think hard about replacing an old oven with other wear. The price is confirmed after on-site diagnosis, with a written estimate before work begins.
The relay board is the part of an LG oven that does the switching: when the control calls for heat, relays on the board close and send power to the bake or broil element. Relays are mechanical, they click thousands of times, and eventually they wear. The code that reports it is F5, and what makes it worth a separate decision is that it can fail in two opposite ways, one that leaves the oven cold and one that is a genuine fire hazard.
| What you find | Likely cause | Lean toward |
|---|---|---|
| F5, timer runs, element stays cold | Worn or open relay contacts | Repair the board on a younger oven |
| Burning smell from behind the panel, element stays hot | Welded relay contact | Switch the breaker off, repair at once |
| F5 with a visibly failed element | Shorted element overloading the relay | Repair the element and test the board |
| Odd, unresponsive controls with F5 | Board signals corrupted | Repair or replace the board |
| F5 on an oven past 13 years with other wear | Board at end of life | Weigh replacing the oven |
What Does F5 Mean on an LG Oven?
F5 means the control board has detected a failure in one of its internal relays. The F5 page rates it high severity, and the range version, on the range F5 page, reads the same. Both describe a relay board failure, so a reset will not repair it, because burned or welded contacts are a hardware fault.
The display shows an active cooking cycle and counts the timer down while the cavity stays at room temperature, or the code appears at startup, during preheat or at one point in a cook. Buttons may flicker or stop responding as signals between the control boards are disrupted.
Is It Safe to Use an LG Oven With F5?
No. The page says not to use the oven, and the reason is the welded-relay case: a relay that sticks closed can keep an element on indefinitely, and nothing then regulates the temperature. An open relay is less dangerous but still means the oven cannot control its heat.
If you smell burning from behind the control panel or inside the oven while F5 is showing, switch the oven off at its breaker and do not restart it.
Relay Board Repair or Replace: The Three Facts
For an LG oven relay board repair or replace comparison, three facts do the work: the age of the oven, whether the board is the only fault and the written estimate. This site's oven control board repair starts from $250, which the cost guide calls the expensive end of oven repairs, and that is the number to hold against the other two.
- Age. The site puts LG ranges at 13 to 18 years of life, so a ten-year-old oven still has years of use ahead, and a board repair is easy to justify.
- Whether the board is the only fault. A shorted element can have damaged the relays; if the element is replaced and the board is not tested, F5 comes straight back.
- The estimate. The price is confirmed after on-site diagnosis, with a written estimate before any part is ordered.
Can You Tell a Shorted Element From a Bad Board?
Not by looking at the display, and that is why the diagnostic matters. Both can produce F5, and the cost differs: an element is a modest part, while a board is the most expensive component in the oven. The cost guide says to confirm the diagnosis before replacing a control board because relay failures can be caused by something downstream.
A technician tests the element's resistance and looks for a short, then checks the relay output. Ask for the result of both before you approve a board. If the element is shorted, the repair may be the element alone plus a check of the board, and the final bill is smaller.
What the Diagnostic Visit Does
Because the cheap cause and the expensive one share a code, the visit follows a fixed order, and it is worth knowing so you can ask for the results.
- Reads the code and the pattern. At startup, during preheat or at one point in the cook, each says something different about the relay.
- Tests the bake and broil elements. A shorted element is ruled in or out first, since it can be the real cause.
- Checks the relay output. The relay board is tested to see whether it switches power on and off cleanly.
- Looks for heat damage. Burned terminals or discoloration behind the control panel are noted before anything is ordered.
The result is a named part and a written estimate, and only then does the decision between repair and replacement begin. Keep that estimate: if you decide to replace the oven instead, it also records what was wrong, which is useful if the old oven is sold or passed on.
Two practical points apply whichever way you go. Do not keep resetting the breaker to coax the oven through a cooking session, because the code is telling you the oven cannot switch its heat reliably. And do not leave the oven switched on at the panel while you wait for the visit; the breaker is the right way to isolate it.
When Repair Wins
Repair wins when the oven is within its range of life and the fault is confined to the relay board. The oven is built in or freestanding with the same cabinet around it, so a repair keeps the fit, the finish and the installation as they are.
- The oven is under about 13 years old. It has most of its life ahead.
- The relay board is separate. On models that use one, ask whether the repair can be limited to that board.
- The element and sensor test sound. Nothing downstream is killing the relays.
- No second major fault. A single board failure on a sound oven is a good repair.
When Replacing Wins
Replacing wins on an old oven with other signs of wear, when the board has failed more than once or when a renovation changes what the oven should be. The site's own advice is that only board failures on units over 12 years old warrant serious replacement consideration.
- Past 13 years with other wear. A hinge, a latch and a control all aging together.
- A repeat F5. A second board failure suggests something else is overloading it.
- Damage to the cavity or frame. Structural damage is a different decision from a relay.
For the general comparison, see our guide to whether to repair or replace an LG oven, and the cost table in the LG oven and range repair costs guide. LG oven repair tests the element, the relays and the board together, and you can schedule a visit or contact us with the code and the model number.