A centre or small-area grill setting may intentionally heat a narrower area. Confirm the selected grill width before concluding that an outer section is broken.
What the observation means
A tray wider than the active grilling area can produce a sharply different result at its edges. Turning the temperature up does not extend the selected coverage. The useful distinction is whether a small grill was chosen, whether the oven offers a separate full-width mode, and whether the change also occurs on that confirmed full-width mode. Observe the food result rather than staring at hot elements.
A useful next step
Choose the grill function specified for the amount and position of food, following the manual's shelf and door instructions. If full-width grilling now leaves one side consistently untouched, note that pattern and which controls were selected. Do not remove a guard, reach towards an element or use reflective foil to try to redirect heat towards the cold area.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.