How to Troubleshoot & Replace Lg AP5989951 / EBG61305805 Thermistor

Replaced thermostat on rear of oven and that was it. I tested continuity after removal and failed, and also malformed so you could tell was bad. Thermostat on top of unit was good. Recommend buying both when purchasing as found several posts of either failing although the rear was more common - seemed to be different parts but not sure if interchangeable. We used the oven earlier that day at 500 degrees so assume that's what cause was. We've run self clean in the past and may have been contributing factor. 

This site is great for the DIY'r...The oven diagram was spot on, I ordered the parts, received them within 2-3 days, then repaired my oven in less than 45 minutes...I spent $20 got it all fixed up...If I called in an appliance repair service, it would've been well over $100. 

Purchased and replaced the Oven Thermistor. 

Replace thermistor sensor. 

I bought the appropriate thermister replacement for our oven model. The fix was pretty easy. The hardest part was that we had to pull out the oven to get to the back. We had to take off the back panel to release the thermostat connector. 

After 6 months of waiting for callbacks from repair shops, I investigated the problem myself. The repair seemed to be straight forward the igniter was inoperable. Ordered the part and fortunately, I was correct in my diagnosis and we are back in business. Only took 10min to change out. 

I first ordered a new PCB and replaced it. This did not solve the problem and the F9 error remained. I measured the thermistor resistance and that looked OK. I then checked to see if the gas valve was getting an on signal when the bake mode was activated. Both the old and new PCB's provided this but the oven did not heat up. Then ordered and replaced the valve. This fixed the problem. 

Replaced circuit board and thermocouple. (temp sensor) 

New temp thermistor PTC. 

Ordered the Thermistor.