LG Oven Temperature Not Right — Causes & Fix

Whether an LG oven's temperature problem is a quick calibration or a real part failure comes down to one question: is the error consistent or erratic? An oven that is always off by the same amount usually just needs calibration or a drifted sensor; one that swings unpredictably or takes forever to heat has a failing element or relay. LG ranges with ProBake Convection add a fan into the mix, so the fix depends on which mode misbehaves.

Quick Answer#

How LG holds temperature#

An LG oven runs a closed loop: you set a target on the ERC, the ERC switches the elements through heavy-duty relays, and an NTC thermistor reports the cavity temperature back so the board can cycle the heat on and off. Every link in that loop can introduce error — a drifted sensor misreports, worn relays under-deliver voltage, and a partial element under-heats. After preheat stabilizes, a healthy oven should hold within about ±10°F of setpoint.

Most Likely Causes, Ranked#

Sensor drift vs. calibration#

The NTC thermistor slowly changes its resistance after years of cycling between room temperature and 500°F and up, and even a small drift produces a meaningful temperature error at cooking heat. The tell is scale: a consistent error around 40 to 75°F usually means the sensor has drifted and should be replaced, while a smaller consistent error around 10 to 35°F is exactly what LG's user calibration is meant to correct — the range allows an adjustment of up to ±35°F to true it against an independent thermometer.

Element and convection faults#

A heating element can develop a high-resistance section that still passes current — so the ERC sees it as "on" — while it produces only 30 to 50% of its rated heat, which shows up as an oven slow to reach temperature and under-baking. In ProBake Convection mode, the fan distributes heat from the rear element through the cavity, so a fan that is not turning can leave the sensor reading correctly near the element while the rest of the oven runs cool. That mode-specific unevenness is the clue that points at the convection fan rather than the sensor.

Relay degradation#

Aging relay contacts on the ERC pit and oxidize, adding resistance that reduces the voltage reaching the elements and therefore their heat output. Because the contacts degrade slowly, the symptom is a temperature error that gets worse over months rather than appearing overnight. When calibration no longer holds and the sensor and elements test good, the board relays are the remaining suspect.

How to check it yourself#

1. Measure the real temperature with an independent oven thermometer at food level.
2. Judge consistency — a steady offset points to calibration or the sensor.
3. Apply LG's calibration for a small consistent error (up to ±35°F).
4. Watch preheat time — a slow climb points to a partial element.
5. Compare bake vs. convection results to isolate the ProBake fan.

Verify with a real thermometer first#

The mistake that sends people down the wrong path on temperature complaints is trusting the oven's own display over an independent measurement. Before you calibrate or replace anything, put a standalone oven thermometer at the rack position where you actually cook, preheat fully, and let the oven stabilize before reading it — the number it settles at, and how far it swings, tells you far more than the setpoint does. A steady, consistent offset is a calibration or sensor issue and is often correctable from the control panel. A reading that never quite reaches the target, or takes far too long to get there, points instead at a heating element losing output. And unevenness that only shows up in convection modes points at the fan rather than the sensor. Measuring first turns a vague ''it bakes wrong'' complaint into a specific, fixable diagnosis, and it keeps you from calibrating away a real element or fan problem that calibration cannot solve.

DIY or call a pro?#

Running an independent thermometer and applying a calibration offset are straightforward owner steps that fix the most common consistent-error cases. Replacing a drifted sensor, a partial element, a convection fan, or a relay-worn board is a repair better handled by a technician working around the range's high voltage. If calibration does not bring it into line, book a diagnostic and we will confirm which part in the loop is off before ordering it.