Model Number: LRE30453SB
Brand: LG
Age: More than 10 years

I set my range to 425 to preheat, and ended up overheating, followed by an F9 error code. I googled it and it looks like it could need a relay control board. I am not sure how to zero in and be sure of what part needs to be replaced. Any idea how to test the temp sensor and the relay control board?