So I just opened my pool on my new house. First time pool owner. I was getting an HS error and temp was reading 104 which wasn't close. Replaced the thermistor, which corrected that. Now I get an HS error after it lights. It will light and run for 15 secs, shake & shut down presenting the error. I know it wasn't open last season. No clue how to fix. I know I have a bad valve on the pump which creates a leak on the waste line and the plumbing is a bad setup, but it worked for the previous owner. Not sure if it's a pressure issue or a part. Suggestions?