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Ok - this one has me stumped. My gas oven has been having issues heating up. I set the bake function to 350 degrees and the actual oven (measured via standalone oven thermometer) barely cracks 150 degrees. Initially I just purchased a new temp sensor off of amazon and replaced it. The issue did not resolve. Next I took off the oven control board to inspect for burnt runs/solders - everything looks good. Next I did what I should have done first and broke out the multimeter. I checked resistance of the sensor at room temperature and it read good (I think 1080 ohms). Next I set the heat to 500 degrees. The oven only got to ~150 degrees (as indicated by the standalone thermometer - the oven indicated 500 degrees was reached). I read the temperature sensor and it read out ~1900 ohms. This leads me to believe the oven control board is good and the sensor is bad. Next I removed the oven temperature sensor from the oven, put it in a pot of boiling water, and took readings... IT READ PERFECT (~1350 ohms)!!

All of the temperature sensor readings were taken at the back of the sensor itself (little white plug) so I can rule out addition of any resistance due to poor wiring/connections between the sensor plug and the oven control board. I thought the oven thermometer could be bad so I put in a dish of water and set the oven to 350 degrees. Water didn't even come close to steaming/boiling so I'm fairly certain the standalone thermometer is working correctly.

My question is this - what could cause the sensor to work fine off the oven, and then poorly when installed back on the oven? I thought maybe it had to do with the temperature range, but my oven isn't even getting as hot as boiling water (which the sensor read correctly on). I have two prevailing theories:

1. Resistance is somehow being added to the sensor via some sort of physical interference when installed on the oven. Any credence to this? I'm not the best with electronics and resistance so I really don't know.

2. The oven is installed on a GFCI outlet which is causing some sort of weird resistance readings on the sensor. This is my prevailing theory. The oven shouldn't really be on a GFCI anyway so I might try an extension cord and then rewire the GFCI if that fixes it.

Anyone experience anything similar? Thanks.
 

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Was it working fine until recently?

Have you added a new gas appliance?

What size gas line is running to the gas oven? Is it just an oven or is it a range with burners on top? If it has burners, do they work okay?

Have you moved the oven recently? If so, did you shut-off the gas-supply at the shut-off valve near the oven? If so, check to make sure it is fully open. Also, check to make sure that the gas supply line isn't kinked.

Has this been happening since the heating season started?

Also, where do you live? What area of the country?

Just some basic questions to help pin down the issue.
 

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Discussion Starter #4
Was it working fine until recently?

Have you added a new gas appliance?

What size gas line is running to the gas oven? Is it just an oven or is it a range with burners on top? If it has burners, do they work okay?

Have you moved the oven recently? If so, did you shut-off the gas-supply at the shut-off valve near the oven? If so, check to make sure it is fully open. Also, check to make sure that the gas supply line isn't kinked.

Has this been happening since the heating season started?

Also, where do you live? What area of the country?

Just some basic questions to help pin down the issue.
I have not added a new gas appliance. Not sure what the gas line size is but it is a range with burners on top. Burners work just fine.

I have not moved the oven recently but I will check the shutoff valve.

This began prior to heating season.

I live in the new england area.

Thank you for your assistance! I just can't figure out why the resistor could read fine when uninstalled, but then reads incorrectly once installed on the stove.
 

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It's difficult to explain how you got a reading of 1900 ohms from the sensor if the oven wasn't 500 degrees. These sensors are pretty simple and your room temperature and boiling water readings indicate that the sensor is ok.



So if the sensor is ok, that pretty much leaves the control board. It's possible there could be a defect inside the chip that reads the sensor values, and you wouldn't be able to see that by looking at the board.



But before you spend money on a new control board, I would buy a new oven thermometer and verify that the oven really isn't heating up properly. That 1900 ohm reading says it's working ok.
 
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