Hayward h250 ed2 failure error code IF - Hayward H-series Electronic Gas Pool Heater H250

Try replacing thermocouple, pilot assembly usually includes t/C,check all wiring connections.

Low Flow errors are not necessarily real. They can be caused by improper adjustment or a defect of the pressure switch. Locate the pressure switch. Verify that the "switch" makes contact. Adjust the dial, reducing the distance the switch has to travel to engage. This will effectively lower the operating pressure required to operate. Keep adjusting until the unit stays on.

Sounds like it could be the flame sensor.