Temperature Oven is consistently too cool. Temp on control panel says 350 but thermometer in oven says 275. How do I fix this????

I get this service call a lot so lets verify temp before we discuss possible causes set the rack in the middle of the oven hang an oven thermometer in the center of rack set a 350 let run 1 hour check the temp after an hour this gives the oven enough time to cycle and stabilize this will give you the true average of oven, temp placement of thermometer is important plus or minus 15F on either side of 350 is not that much of a big deal the max range for a temperature offset is usually 30F, there should be a tech sheet in a plastic pouch on the back of the unit now if you do find it to be running 50F too hot well there are test to determine if the temperature sensor is operating correctly it should read appx. 1654 ohms at 350 this tells the control board to open the heat relay stopping power to the gas valve lot of work you have to have the oven out back panel off to access the wiring going to control unplug machine at 350 disconnect wiring from board to ohm out sensor, sensors go bad and so do boards, sensor is cheaper try changing it first.

It is normal for the thermal device to turn on and off. Obtaining a steady temp is not always possible. When setting a temperature on some ovens, they have what is called a tolerance point. That means a set temperature has a range of a few degrees up or down. At the Down point, the oven is triggered to energize the coils and bring the interior of the oven back to the settings desired. The other factor is opening the oven and allowing cool air to enter, or in some cases a leaking door seal allows air to enter and heat to escape.

oven does not heat to desired temp we have used a oven thermometer and most of time oven is at 350 but thermometer is at 275 than up to 325 and then down again to 225

This Conversion table is from the old Gas Mark scale
I'm thinking it should be right or at least pretty close.
You could also get a cheap ($5-7) oven thermometer from local grocery store.
Put it inside oven to check actual temp achieved.

Gas mark Fahrenheit Celsius
1⁄4 225° 107°
1⁄2 250° 121°
1 275° 135°
2 300° 149°
3 325° 163°
4 350° 177°
5 375° 191°
6 400° 204°
7 425° 218°
8 450° 232°
9 475° 246°

Standard oven thermometers use a bi-metal coil, which is slow to react. When we test oven calibration, we use digital thermometers with a remote temp probe which are MUCH more accurate and MUCH quicker to respond to temperture changes. If your bake times are significantly longer or shorter than the recipes state, have a service technician test it.

You can have the oven recalibrated by a professional OR you can purchase an oven thermometer and check the temperature yourself. Place the oven thermometer in the oven.Set the oven to a specific temperature. When it indicates it is at that temperature check the thermometer. Adjust your setting by that many degrees. For instance, if you set the temp at 350 and the oven thermometer shows 450, then reduce your temperature setting by 100 degrees each time you use the oven.

The problem is usually the igniter not reaching the correct amp draw .When the igniter does not reach the correct amp draw it may allow the gas valve to partially open or not open at all. The igniters are inexpensive and easy to replace. This video will walk you thru the correct procedure for testing an oven igniter. It may be a different model but the testing will be the same.You can also enter your model # for diagrams and illustrations of your specific model. Not all models are available. All parts come with installation instructions.

From the symptons you describe, I would say that the oven thermostat is faulty, and in need of replacement.
Make sure your thermometer is o/k by checking it against another one, or boil some water, and check the temp of the boiling water, this should determine if your thermometer is o/k.
Hope this helps.

some oven temperature dials are adjustable by pulling knob off,turning a bit and pushing it back on in a different position.use an oven thermometer to determine the accuracy of your control knob.adjust knob or make note of difference between dial setting & thermometer reading.i.e.knob is at 350* thermometer says 300* set knob to 400* to achieve an oven temp of 350. could you E-mail me a slice of banna bread?

i would have to say that there would be a problem with the ignitor and control regulator