Direct answer: If an LG oven runs but will not reach the set temperature, the usual causes are a weak oven bake element or oven igniter, a bad oven temperature sensor, or heat leaking past the oven door gasket.
Most likely: Start by separating the symptom: electric ovens often have a weak or broken oven heating element, while gas ovens often have an oven igniter that glows but is too weak to open the gas fully. If the oven does heat but stays consistently off target, the oven sensor moves up the list.
Watch what the oven actually does during preheat. Does it stay cold, climb partway and stall, or eventually get hot but cook slow? That pattern tells you more than the display does. Reality check: a long preheat with a cold cavity is different from a normal preheat that just feels slower with heavy cookware inside. Common wrong move: swapping the sensor or control first when the real problem is a weak igniter or a partially failed bake element.
Don’t start with: Do not start by replacing the oven control. Controls are possible, but they are not the first bet when the oven still powers up and tries to heat.
The display says preheating, but the cavity never gets properly hot and food stays pale or undercooked.
Start here: Start with the heating pattern. On electric, check whether the oven bake element is heating. On gas, watch whether the oven igniter lights the burner promptly.
It climbs some, then seems to level off well below the target temperature.
Start here: Check for a weak heat source first, then look at the oven door gasket and oven temperature sensor.
Preheat drags out and baking times are longer, even though the oven is not completely dead.
Start here: This often points to a weak oven igniter on gas or a partially failed oven heating element on electric.
The oven reaches heat, but it overshoots, undershoots, or cooks inconsistently from one use to the next.
Start here: After ruling out a torn oven door gasket and obvious heating problems, focus on the oven temperature sensor.
The igniter may glow and still be bad. When it weakens, the burner lights late, lights weakly, or never opens properly, so the oven lags far behind the set temperature.
Quick check: Start bake and watch through the bottom vent or access area if visible. If the igniter glows for a long time before flame, or glows with no steady burner flame, suspect the oven igniter.
A bake element can split, blister, or fail internally and still let the oven show normal controls. The broil may still work, which fools people into thinking the oven is fine.
Quick check: During bake, look for an oven bake element that stays dark, sparks, has a burned spot, or only glows on one section.
If the oven does heat but consistently runs too cool or acts confused about when to cycle, the sensor is a common next suspect.
Quick check: If both heat sources seem to work and the door seals well, but the oven temperature is steadily off in the same direction, the oven temperature sensor becomes more likely.
A torn, flattened, or loose gasket lets heat spill out around the door. The oven may run constantly and still struggle to hold temperature.
Quick check: Look for gaps, hardened sections, torn corners, or hot air pouring from the door edge during preheat.
Wrong mode, delayed start, or a canceled cycle can look like a heating failure when the oven is really waiting or using the wrong heat source.
Next move: If the oven now heats normally, the problem was a setting or cycle issue rather than a failed part. If it still stays cool, heats very slowly, or stalls low, move to the heating-pattern check.
What to conclude: You want to know whether the oven is failing to produce heat or just not being commanded the way you expected.
These two ovens fail differently, and the fastest clue is what the heat source does during preheat.
Next move: If you clearly find a weak igniter on gas or a damaged bake element on electric, you have your main repair path. If the heat source looks normal but the oven still runs cool, keep going to the seal and sensor checks.
What to conclude: A gas oven that glows without strong burner ignition usually needs an oven igniter. An electric oven with a damaged or unevenly heating bake element usually needs an oven heating element.
A leaking door can make a good heat source look weak, especially on long preheats and baking cycles.
Next move: If reseating or cleaning the gasket reduces heat loss and the oven now holds temperature better, the seal was part of the problem. If the gasket is damaged or the door still leaks badly, the oven door gasket is the likely fix. If the seal looks good, move on to the sensor branch.
Once the main heat source and door seal look reasonable, a drifting sensor becomes the next practical suspect.
Next move: If the sensor is visibly damaged or tests out of range with power disconnected, replacing the oven temperature sensor is a supported repair path. If the sensor looks normal and you cannot confirm it electrically, but the heat source is clearly weak, go back to the igniter or bake element path before blaming controls.
By this point you should have a real failure pattern, not a parts dart throw. Finish the repair that matches what you saw.
A good result: If the oven now reaches set temperature in a normal preheat and cycles steadily, the repair path was correct.
If not: If the same symptom remains after the matched repair, the next step is professional diagnosis of the oven wiring or control circuit rather than more guesswork.
What to conclude: The common fixes here are the heat-producing part, the temperature-reading part, or the seal. Controls are farther down the list and should be proven, not assumed.
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Usually because the oven is trying to heat but the main heat source is weak. On gas ovens, that is often a weak oven igniter. On electric ovens, it is often a failed oven bake element. A bad oven temperature sensor is more likely when the oven does heat, just not accurately.
Yes. That is one of the most common gas-oven failures. The igniter can glow orange and still be too weak to pull enough current to open the gas valve properly, so the oven heats slowly or never reaches temperature.
Because bake and broil use different heating parts. If broil works but bake does not, the problem usually stays on the bake side: a weak oven igniter on gas or a failed oven heating element on electric.
It can. A torn or flattened oven door gasket lets heat escape, so the oven runs longer and may struggle to hold temperature. It is usually not the cause of a completely cold oven, but it can absolutely cause slow preheat and weak baking performance.
Not first. If the display works and the oven attempts to heat, the control is not the best opening guess. Prove the oven igniter or oven heating element, the oven temperature sensor, and the oven door gasket before spending money on an oven control.