Classic symptoms of a gas oven thermostat dying?

Anyone had this problem with a GE gas oven please?
First, the internal auto-probe started undercooking everything, but when I replaced the probe, it did nothing. I figured the problem may be with the t hermostat?
The oven thermometer was drastically under-reading, leading to my only bein g able to judge cooking times with an 'external' temp probe
Now, using an internal add-on thermometer to judge the real internal temp, the reading on the panel under-reads badly. But when I try to compensat e, over-adjusts just as badly. the oven't internal thermometer (as shown b y the panel) reads 375 when the real temp is 250. But if I set temp t o 425 (thinking that I will get about 375), the add-on thermometer rushes u p to 500!
If I then try to get the temp in the oven down, the oven over-reads all the way down to about 300, when it is only about 25 degrees off.
So the panel temp seems to be about 75 degrees off (that is way outside the level of adjustment on the panel: I Have tried to adjust that and it doesn 't seem to make any difference to how badly the panel reads the temperature )
Am I likely to be able to fix this by replacing the internal thermostat at the rear of the oven on the wall, judging by these symptoms please? Or is this sort of haywire-reading something else?
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On Monday, October 6, 2014 10:42:00 AM UTC-4, Amanda Ripanykhazova wrote:

thermostat?

ate, over-adjusts just as badly. the oven't internal thermometer (as shown by the panel) reads 375 when the real temp is 250. But if I set temp to 425 (thinking that I will get about 375), the add-on thermometer rushes up to 500!

sn't seem to make any difference to how badly the panel reads the temperatu re)

s this sort of haywire-reading something else?
It sounds like the likely culprit is whatever they use in that oven as the temp sensor. Whether that is the "internal thermostat" at the rear of the oven or not, IDK because we have no clue which GE oven this is. I would doubt that "internal thermostat" is the right term. It sounds like a modern electronic one and I would think they would use a sensor which then interfaces to the control electronics, ie there is no separate themost at.
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Thank you for that and sorry if my term thermostat was wrong: You are absolutely correct, what is in this GE PGB918SEM is a temperature sensor. It doesn't govern anything at all in the way a thermostat would: It just READS as you correctly note
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On Monday, October 6, 2014 11:11:35 AM UTC-4, Amanda Ripanykhazova wrote:

So it;s off by 125 deg and the most likely culprit is that temp sensor.
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Yes, and the mis-reading isn't uniform, making it even more likely that it has gone bad.
It seems to cost about $20 though slightly ominously there is something called a re-certified one on ebay??
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Anyone had this problem with a GE gas oven please?
First, the internal auto-probe started undercooking everything, but when I replaced the probe, it did nothing. I figured the problem may be with the thermostat?
The oven thermometer was drastically under-reading, leading to my only being able to judge cooking times with an 'external' temp probe
Now, using an internal add-on thermometer to judge the real internal temp, the reading on the panel under-reads badly. But when I try to compensate, over-adjusts just as badly. the oven't internal thermometer (as shown by the panel) reads 375 when the real temp is 250. But if I set temp to 425 (thinking that I will get about 375), the add-on thermometer rushes up to 500!
If I then try to get the temp in the oven down, the oven over-reads all the way down to about 300, when it is only about 25 degrees off.
So the panel temp seems to be about 75 degrees off (that is way outside the level of adjustment on the panel: I Have tried to adjust that and it doesn't seem to make any difference to how badly the panel reads the temperature)
Am I likely to be able to fix this by replacing the internal thermostat at the rear of the oven on the wall, judging by these symptoms please? Or is this sort of haywire-reading something else?
--

I can't help with the electronics, but if you want to see if the
thermostat is in the right place, you could set a bimetal thermometer
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Yes, that is what I have been using to determine that the reading on the panel is wrong, though it hadn't occurred to me to try in different positions to determine that it is even worse than i thought.
It should have, as I put it at the very front of the oven whereas the sensor is at the back AND I have often wondered why the oven's self-cleaning function doesn't actually work at the very front of the oven!
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On Monday, October 6, 2014 11:25:49 AM UTC-4, Amanda Ripanykhazova wrote:

I would put the the thermometer near where the sensor is not at the opposite end. I can't imagine a 125F difference between front and back, but it would be better to measure temps at the same location.
It's possible that as you point out, the temp sensor is why the self-cleaning doesn't work right too.
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I wasn't going to make a big deal about this but I had noticed over the las t 10-15 YEARS that self-clean never actually cleans the front panel, where the glass is: Neither on my old unit which had a 2 hour cleaning cycle, nor on this newer one with it's 3 hour cleaning cycle.
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