We are having the same problem many have posted about - start up heater, once the ignition kicks in, it blows hot for 10 -20 seconds, then turns off and displays E05. On the control board, the SFS light is lit along with LED11 (service heater). We replaced the SFS yesterday and still get this error code. Interestingly, this happens about 90% of the time, but 10% of the time, it runs without an error code (earlier today, in fact, we had it running for a couple hours then turned it off and now only getting E05 again). We had the pool service company here about 2 weeks ago, and during that time, the error code never showed up (annoying), so they couldn't diagnose. I am thinking the next step is replacing the control board ($300), but wanted to see if anyone else has other thoughts on what could be causing this?