Finding out your oven will not turn off can be quite alarming. However, it is not as uncommon as you may think. Typically, with this issue, the only way to stop the oven from heating is to unplug it or turn it off in the electrical panel (breaker box). The most common causes of the issue are a fault with the control board or a damaged heating element. The easiest cause to diagnose is to simply inspect the heating elements, where you should be able to see if they are damaged.
Safety First
Ovens typically have sharp edges, so it is best to wear protective gloves when repairing an oven. Ovens also have the potential to cause a fire if the repair is not done correctly. Therefore, it may be best to call a trained professional to fix your oven.
1. A Fault with the Oven Control Board
The most common reason why an oven will not turn off is that one of the control board’s relays has shorted. The control board’s relays send voltage to the bake and broil circuits. If one of these relays shorts, the board can end up sending continuous voltage to the heating circuit, meaning the oven continues to heat and will not turn off.
It is difficult to test the control board, so you will need to perform a visual inspection. If the control board doesn’t appear to be damaged, you should check other causes of the issue before potentially replacing it.
Check and Replace the Control Board:
- Make sure the power is turned off in the electrical panel.
- Remove the back panel on the oven. Depending on the oven, you may need to remove the top panel as well.
- Inspect the control board for damage.
- If the control board is damaged, take a photo to remember where each wire goes before removing it from the oven.
- Disconnect the wires.
- Unscrew the mounting screws.
- Remove the control board.
- If your new control board does not have an overlay, carefully remove the old overlay with a putty knife, and attach it to the new control board.
- Align the new control board and secure it with the mounting screws.
- Reattach the wires to the control board.
- Reattach the back panel; then reconnect the power.
2. Damaged Bake or Broil Elements
Another common reason why an oven will not turn off is that either the bake or broil element has shorted out. The bake element is found at the bottom of the oven, while the broil element is at the top. Often the defective element will appear damaged, with either a piece having broken off or the element appearing blistered.
With the power disconnected and the element given time to cool down, inspect the element for damage. The element can also be tested with a multimeter to determine if it needs to be replaced.
Check the Element with a Multimeter:
- Make sure the power is turned off in the electrical panel.
- Remove the oven’s back panel.
- Disconnect the heating element wires at the back of the oven.
- Use a multimeter to test the heating element’s terminals for continuity. The element can also be removed from the oven and tested if you cannot access the back of the oven.
- If there is no continuity, the element will need to be replaced.
- Test that the element has not shorted through the frame of the oven by touching one multimeter probe to one of the element’s terminals and the other to the metal back of the oven. Note, if the surface is painted, this test will not work. If there is continuity, then the element has shorted and will need to be replaced.
3. Check the Temperature Control Thermostat
The oven’s temperature is regulated by a thermostat. Sometimes, the thermostat can overheat and cause the electrical components inside the thermostat to weld together. If this has happened, then the thermostat could be constantly calling for more heat, even though the oven is turned off.
On most ovens, the thermostat is located behind the temperature control knob. Depending on the type of oven, if you turn the temperature control knob, you will hear it clicking as you turn it. If there is no clicking, it indicates that the thermostat is defective. If the thermostat is faulty, it will need to be replaced.
Check and Replace the Thermostat:
- Make sure the power is turned off in the electrical panel.
- Remove both the rear and top oven panels to access the thermostat.
- Locate the thermostat behind the temperature control knob.
- Take a photo to remember how the wires connect to the thermostat.
- Disconnect the wires to the thermostat.
- Test the thermostat with a multimeter.
- To replace a faulty thermostat, you will likely need to disconnect the thermostat from the temperature control knob.
- With the knob removed, unscrew the screws holding the thermostat in place.
- Release the capillary tube (sensor), which is located inside the oven cavity. The capillary tube can usually be released by carefully pulling it off the clips that attach it to the rear of the oven cavity.
- Behind the oven, remove the capillary tube, which should be connected by a wire to the thermostat. You should now be able to remove the thermostat, with the wire attached to the capillary tube, from the oven.
- Install the new thermostat by securing the mounting screws and putting the temperature control knob back on.
- Thread the new capillary tube into the oven. Be careful not to damage the capillary tube, as it is delicate, and if damaged, it will not work correctly.
- Reconnect the wires to the thermostat.
- Clip the capillary tube into place inside the oven.
- Reattach the back and top oven panels.
- Reconnect the power to the oven.
4. Defective Relay Board
Depending on the oven, it may use a relay board to control the voltage to the heating element. If the relay board is defective, it may be sending continuous voltage to the heating helmet, causing it to continue heating when the oven is turned off.
5. Defective Controls
The physical knobs, dials, and switches may be broken or dirty. Check the controls for cracks and other signs of wear and tear. You may need to access the rear of the control panel to thoroughly inspect the controls and assess if they are working correctly.
