Safety first: Isolate power at the breaker before working on the oven.

Check sensor connection: Remove the oven from the cabinet if necessary to access the rear. Locate the sensor connector where it passes through the rear panel and ensure it is fully seated.
Test continuity: Disconnect the sensor from the harness and measure resistance across the sensor. If the meter shows OL (open line), the sensor is defective and must be replaced.
Check harness continuity: With the oven pulled out and the top or rear panel removed, disconnect the harness from the control board and test continuity from the board connector to the sensor connector. Repair or replace the harness if open.
Inspect control board: If both sensor and harness are good, the main control board sensor circuit may be faulty. Look for burnt spots or damaged traces. Replace the control board if necessary.
Reassemble and test: After replacing any parts, restore power and run a preheat cycle to confirm the F3 code does not reappear.

Oven does not reach set temperature, display shows F3 during preheat or shortly after starting.

Possible Causes