Oven worked just great until half way through cooking last night. Preheat light started beeped and started blinking along with the cook time on/off button. Reset the oven to off waited a few then turned it back on. Within a few seconds, preheat light came on and did not heat. Unplugged oven from wall and waited about 1 minute then plugged back in, oven came on for a bit then did same thing.
Next tried just the broiler and it worked for a bit then the same thing. Unplugged again and waited awhile. Noticed that if I left the door openand turned on element would glow red shut off for about 30 seconds and continue like this for about 10 minutes before going back to the flashing preheat and cook time.
Last thing I tried was the self-clean. I ran this for about 10 minutes and all worked great until I opened the door, then the same flashing happened.

I looked in the owner's manual and noticed one of the fault codes being:
Preheat Light Flashing with control knob in any position except "OFF" = Shorted/Open Sensor or Sensor Circuit Shorted to range frame.

I did just install this over about 5 days ago, moving it from my Father-In-Laws house to mine. We heated items up with no problem about 5 times before this happened.

Once again the range is a GE model number is a JBP series, not sure of which one but manual is for ranges 21-48 I believe (at work).

Thanks.

Model # J BP46G S1WW
As soon as I turn on the oven, the Preheat button starts blinking and there is no heat. The cook top heats up fine.
What do I do?
Thanks!