GE oven model jtp55com1cc controller has s calibration problem. To get 425 deg F the oven must be set 50 to 70 degrees above. Both ovens have similar problems.

SOURCE: F2 Oven overheats

jaz3133, it's probably the temp sensor that has gone bad. You should be able to get it from the front. It's the probe that comes out from the back wall of the oven. You can have someone ohm it out. Should read approx 1100 ohms at room temp. Part number for the temp sensor is WB20K5040. Make sure power is off befor removing the sensor. Catriver..post back.

SOURCE: NEFF Oven Model B1430NOGB/02 Oven Temp not heating above @50 degrees

probably the element. to save wasting money, check continuity with a multimeter

SOURCE: GE double oven - bottem will not heat, top oven fine

I had a similar problem. Solved mine by resetting the manual reset thermal switch. The switch for the top oven is located behind the control panal which can be removed easily by taking out three screws then lifting up an leaning out. The switch has a red reset button, just push it in till it clicks.

For safety, SWITCH THE BREAKER OFF WHILE YOU DO THIS!!!

The lower oven switch is located behind the vent grill between the two ovens.

GE should be ashamed of hiding this feature-it isn't mentioned in the manual. I discovered it on a schematic hidden behind the control panal.

Good Luck, DVS1936

SOURCE: gas oven won't light on bake setting

If the bake ignitor comes on (starts glowing) - check the amperage on the bake ignitor wires when it's on. If the ignitor is a round style - amperage should be 2.5-3A, if the ignitor is rectangular - 3 - 3.6A. If less than 2.5A or 3A respectively - replace ignitor. If the ignitor does not come on - check the voltage on the ignitor, should be the line voltage 110-120v AC. Faulty gas valve is uncommon, but still a small possibility. Ignitor part numbers for round style ones: 4342528, WB2X9154, SGR403, 5304401265;
rectangular styles: 12400035, WB13K21, WB2X9998, SGR412, NR020, 5303935066, 814269, 9753108.
Ignitors of the same shape (i.e. rectangular) are interchangeable, if you can splice the wires.

PS For your model number the original part number was WB13K4 or WB13K0004, which is a round ignitor, though on the breakdown a rectangular one is shown, so check carefully.

Good luck!