Direct answer: If your LG oven takes too long to preheat, the usual causes are a weak oven igniter on a gas oven, a failing oven heating element on an electric oven, a bad oven temperature sensor, or heat leaking past a worn oven door gasket.
Most likely: Start by watching how it heats. A gas oven that clicks and eventually lights often has a weak oven igniter. An electric oven that preheats slowly or never quite catches up often has a weak bake element or a bake element that is heating only partway.
Separate gas from electric first, then look for the physical clue that fits. Reality check: many ovens still heat with one weak component, so the problem feels like slowness instead of a total no-heat failure. Common wrong move: trusting the display alone without checking whether the oven is actually climbing temperature at a normal pace.
Don’t start with: Don’t start by ordering an oven control board. Slow preheat is much more often a heat-source or temperature-sensing problem.
You hear clicking or see a glow, but the burner does not light right away and preheat drags out.
Start here: Start with the igniter branch. A weak oven igniter can glow and still be too weak to open the gas valve quickly.
The oven eventually gets hot, but it takes much longer than it used to and recovery after opening the door is poor.
Start here: Check the bake element first for dead spots, blistering, or sections that are not heating evenly.
The tone sounds normal, but the cavity still feels cool and food needs extra time.
Start here: Check actual temperature behavior with an oven-safe thermometer and consider the oven temperature sensor if heat sources look normal.
You feel strong hot air at the door edge, see a loose seal, or notice the kitchen gets unusually hot during preheat.
Start here: Inspect the oven door gasket and door closing fit before chasing electrical parts.
This is the most common slow-preheat pattern on gas ovens. The igniter may glow or click but take too long to light the burner, so the oven heats in lazy bursts.
Quick check: Start Bake and watch through the bottom opening if visible. If ignition is delayed well beyond the normal short wait, the oven igniter is the lead suspect.
A bake element can partially fail and still warm up some, which makes preheat slow instead of completely dead. You may see bright spots, blisters, or a split in the element.
Quick check: During preheat, look for even heating along the full bake element. A section that stays dark or damaged points to the oven heating element.
If the sensor reads wrong, the control can stop or reduce heat too early, making the oven claim it is ready before the cavity is actually hot.
Quick check: If both heat sources seem to work but actual temperature lags far behind the set temperature, the oven sensor moves up the list.
A leaking door seal lets heat spill out during the hardest part of the cycle, which is preheat. The oven may still work but take longer and struggle to recover.
Quick check: Look for gaps, tears, flattened sections, or spots where the oven door gasket will not stay seated.
Wrong mode, delayed start settings, or a door not fully closed can mimic a heating problem and waste time.
Next move: If preheat time returns to normal, the issue was setup or loading, not a failed part. If it is still slow with a basic empty-oven Bake cycle, move on to the heating pattern check.
What to conclude: You have ruled out the easy false alarms first.
Slow preheat means different things on gas and electric ovens. Splitting them early keeps you from chasing the wrong part.
Next move: If the pattern clearly points to one heat source, you now have a likely repair path instead of guessing. If the heating pattern is not obvious, check actual temperature and heat loss next.
What to conclude: A gas oven with delayed ignition usually points to the oven igniter. An electric oven with weak or uneven lower heat usually points to the oven heating element.
A bad seal can add several minutes to preheat and make a good heating system look weak.
Next move: If the gasket was loose or dirty and reseating or cleaning it improves preheat, keep using the oven and monitor it. If the seal looks decent or fixing its seating does not change anything, check temperature accuracy next.
This tells you whether the oven is truly heating slowly or just reporting temperature badly.
Next move: If the thermometer and display are close and preheat time is reasonable, the oven may be operating normally for that load and setting. If the display and actual temperature are far apart or the climb is abnormally slow, you have enough evidence to target the likely failed component.
By this point, the common repair paths are usually clear enough to act on without shotgun parts buying.
A good result: If preheat time returns to normal and the oven reaches and holds temperature, the repair path was correct.
If not: If the same symptom remains after the matching repair, the problem may be wiring, relay output, or another control issue that needs deeper testing.
What to conclude: Most slow-preheat ovens are fixed by the heat source, sensor, or seal. Controls are possible, but they are not the first bet.
Repair Riot may earn a commission from qualifying purchases, at no extra cost to you.
That usually means one part is weak, not completely dead. On a gas oven, the oven igniter is the top suspect. On an electric oven, the bake element often weakens or fails in one section. A bad oven sensor or leaking door gasket can also stretch preheat time.
Yes. That is a very common field failure. A weak oven igniter can glow and still fail to draw enough current to open the gas valve quickly, so the burner lights late and preheat drags out.
That points more toward temperature sensing than raw heating power. The oven temperature sensor may be reading off, or the oven may be heating unevenly enough that the control thinks it is ready before the cavity really is.
It can. If the gasket is torn, flattened, or loose, heat escapes during the hardest part of the cycle. You will often notice extra heat around the door edge and slower recovery after opening the door.
Not first. Slow preheat is much more often caused by the oven igniter, oven heating element, oven temperature sensor, or oven door gasket. Control problems are possible, but they are farther down the list and usually need better testing before you spend money there.