Oven overheats and burns food even at low temperature settings

Safety first: Disconnect power immediately if the oven overheats uncontrollably.

• Test sensor: With power off, measure the oven sensor resistance. A very low reading suggests a shorted sensor that misreports temperature.
• Inspect control board: Look for a relay that appears welded or burnt. If the element stays on even when the oven is off, the relay may be stuck closed.
• Check wiring: Confirm that elements are wired according to the Hitachi wiring diagram and not directly to live without control.
• Replace faulty parts: Replace the temperature sensor first. If overheating persists, replace the main control PCB or thermostat as required.