Edward W Southington , CT December 27, 2016 Appliance: General Electric Electric Range PP950BM1BB F123 error code lr burner not functioning lr burner hot light always on No direct hits on F123 code for my GE profile 30" glass cooktop using Google searches. Stumbled on "similar" symptoms saying it's probably the sensor integral to the heater element, so just replace the element as a complete unit. I am a very mechanically inclined person and still found it a sort of scary endeavor given then potential cost of being wrong and also taking apart a very expensive cooktop just to get to the point of being able to swap in the new LR element unit. Scariest part was how cheaply constructed this GE Profile cooktop is. For the $$, I figure it would have been a bit more robustly built. But it has worked flawlessly for the last 9 years, so I guess good enough quality...and it does look good in the kitchen. I was also nervous about a "calibration" procedure which also had very little info from Google searches. The replacement part came with calibration instructions and the "aluminum disk" needed. Overall, a very easy repair...because everything went right and the thing works again. Read More... 7 People found this story helpful Do-It-Yourself Rating: Repair Time Estimate: 1-2 hours Tools: Screwdrivers, Socket Set