I've been chasing an SFS LED problem for two years. The heater fires and runs for 30-90 seconds, then quits with SFS LED lit. I used to be able to reset via automation and eventually the heater would get through this early shutdown and run all day, but now it never makes it through the initial 0-90 second period. When the problem first occurred two years ago, I replaced the sensor with an aftermarket and the problem didn't get better, but I limped along. Now that limping no longer works, I've replaced with a Pentair sensor and still have the problem. Sensor temp spikes to high 400s. I've tried most of the solutions on this forum short of complete dismantle to check for soot. Finally, I unscrewed the sensor and left it out and the heater ran fine. Meat thermometer spiked to 390 and settled to 350. I feel like I've isolated this to the SFS sensor/circuit by removing it and running the heater. I'm sure it's a bad idea to run the heater long-term without the sensor, but how many must I buy to get a good one? I feel like if I could just get past that initial spike, I'd be fine. Is there a way to increase the SFS temp trip level or add a delay into the trip function? Separate question: Does the firmware or software version of the heater ever need to be updated and how can I do it?