Oven takes an unusually long time to preheat or never reaches the set temperature.

Safety first: Turn off power before testing components.

• Verify supply voltage: For electric ovens, confirm 240V supply at the terminal block (performed by a qualified person). Low voltage will cause slow heating.
• Element inspection: Check bake and broil elements for cold spots or discoloration. Test resistance and replace any element that is open or significantly out of spec.
• Sensor test: Test the oven temperature sensor resistance at room temperature. Replace if out of range.
• Door seal: Inspect the door gasket for gaps or damage that could allow heat loss. Replace if necessary.

Note: Use an oven thermometer to confirm actual temperature during diagnosis.