As we sneak up on Thanksgiving no doubt you would like to avoid this scenario: An evening or so before Turkey Day: … you run a self-clean to get ready to roast the big bird … next morning: oh-oh!
Among other things, at FixYourBoard we repair oven controllers. Often the description that accompanies the failed controller starts with “After running a self-clean cycle … “.
Here I will discuss the causes that we’ve seen and what to do about it. But first, here’s an important tip:
Tip: Do not run self-clean a day or two before a big event!
If you have the urge to run self-clean before an important event, RESIST, DELAY! Wait until after the event. Do it when you have adequate time to repair in case it results in a failure.
Understand that, from what I’ve seen, I believe that most of the self-clean induced failures will happen eventually even without help from the self-clean cycle (naturally at the most inconvenient time) but that the high temperature developed during self clean speeds up the failure process. So, only run self-clean when you have enough lead time for a repair job just in case it results in an oven failure.
Error Code Flashing (Error Code Examples Here for Typical GE Electric Oven)
Not to pick on GE, but I read that they invented the self-clean feature, which is very innovative I might add. We repair these controllers often, so I will use their oven as an example. Please be aware that the meaning of the error codes change between manufacturers and models. They are listed in the tech sheet which is taped on the inside of the oven keypad/control panel on most ovens. The discussion here is valid for many models but obviously the details may vary for your specific unit.
F0, F1, F8, FF Errors
These errors generally mean the control board has failed in one or more ways. F1 is by far the most prevalent. When this happens you need to replace the control board. You may be able to buy a new board or have us (www.fixyourboard.com) repair it (particularly useful if the board has been discontinued by the manufacturer). We have many DIYers who remove their control board and send it in for repair.
On some models it is possible that F1 could also be caused by a keypad problem. In this case it will specify in the tech sheet to power down the oven, disconnect the keypad then power the oven back on, wait for a few minutes to see if the error reappears. If the error reappears it is definitely the control board. If not, it is probably the keypad but be aware that F1 usually starts out as being an intermittent fault, then gets more prevalent with time.
This means that the controller has detected, or at least “thinks” it detected an over-temperature condition. While it may not be apparent whether or not the oven actually did overheat, there are two cases to consider:
Case 1: F2 Error is registered and the oven DID actually overheat.
Usually this is caused by the Bake and/or Broil relay contacts welding themselves shut. This may not be as obvious to observe as one would think. Most (not all) ovens have a “Double Line-Break” relay as a safety device. It’s purpose is to disconnect power to the Bake/Broil elements in case of a fault condition. So the oven may still be able to turn itself off, but when it heats it will heat too rapidly and may over-shoot the set point enough to cause an F2 Error. If the oven design has no safety relay then it will be obvious, the power will need to be shut off to kill the heat. If a relay has failed the control board needs to be replaced or repaired.
Now, you may be wondering: How do they protect against a welded relay using another relay in series with the first one? If not, skip this paragraph. Why don’t they both weld themselves shut? The bake/broil relay contacts wear as they are turned on and off due to arcing from the current and voltage in the circuit. The control board makes sure that under normal conditions the “Double Line-Break” is only energized before the Bake/Broil relays and only released after. That way its contacts never switch when current is flowing, except in a fault condition. So if the need to break the circuit occurs, chances are high that the Line-Break relay will still be in good shape.
Note that the temperature required to trip F2 depends on the state of the door lock. If the oven is in a normal cooking mode (door unlocked) the trip point is a little above 550 degrees F. If the door is locked, the trip point is raised to slightly above the maximum expected self-clean temperature.
Case 2: F2 Error is registered but the oven DID NOT overheat.
This is caused by a failure somewhere in the temperature sensing circuit which consists of the temperature probe, its wiring connections and the measuring circuit on the control board.
The first thing to check it the temperature sensor. Unplug it from the control board and measure its resistance at room temperature. If it comes in near 1100 ohms, chances are, your sensor is fine.
Even though the sensor itself is fine, we sometimes see a problem caused by oxidation of the connector pins causing a higher than normal resistance, which makes the controller think the oven is hot. In this case they need to be cleaned, re-tensioned or replaced. This oxide build up can be accelerated by the high temperature self-clean operation.
If the sensor and connections check out then the problem is in the measuring circuit of the control board. Again, it can be sent in for repair or replaced.
F3 and F4 Errors
F3 means the controller has detected an open circuit in the temperature sensor path. Usually this is an extreme case of the causes of F2, and may accompany it.
F4 is a shorted sensor. Look for pinched leads or scraped insulation on the wires going to the temperature probe.
F5 Error: Door Lock Failure
Sometimes the oven fails leaving the door in a mechanically locked condition. I will defer to my colleagues who make service calls to comment on some tricks to fix the mechanics of this. There are two limit switches on the lock mechanism which tell the controller whether the door is open, closed or locked. And, of course the lock motor itself, which is energized by a relay on the control board. This error code means that the limit switches did not register the expected response after a lock motor operation.
The controller has detected a stuck key on the keypad. Push each key followed by cancel to check if the keypad is functioning. You should hear a beep or see a function change (with the exception of up/down arrows, they need a time or temperature setting function first) for each key. Sometimes you can clear a stuck key but this will probably be temporary in which case you should be thinking about a new keypad.
Other symptoms of control board failure
We see two frequent board failures that don’t throw error codes.
First is where bake or broil modes will start but the oven will not come up to temperature. But first check the temperature probe and the elements themselves as they can cause a similar symptom. The telltale sign is if the temperature displayed by the controller is significantly higher than the actual oven temperature and the probe has checked ok.
Second is a case where bake will start, then about 30 seconds later it will reset itself as if you had pushed the cancel button.
I hope I have shed some light on various oven control board failure mechanisms and symptoms. If you determine that you have a defective control board, and particularly if it has been discontinued or made obsolete by the manufacturer, we hope you will give us a chance to fix it for you at FixYourBoard. We like to keep this stuff out of the landfill and save you some money to boot. In a future blog I’ll provide some tips on removing and replacing control boards.
Thanks for reading and have a safe and happy Thanksgiving.