My heater work periodically, when it doesn't it will turn on, and I get the 128 and r=5 messages then it doesnt start. If I hit pool or spa nothing happens. Sometimes it works great but most it doesn't do anything. I get no error and diagnostic light shows nothing. I've checked flow sensor and I think that's the only one that would prevent from even trying to start?? Gas is one and of course it has power. What can I check next?
