I was getting the IF code this spring right before we began using the pool for the summer. I turned off the heat pump this last week, because it was struggling to keep up now that it has gotten cold here. I went to troubleshoot the gas heater. I've been through all the steps I can find from Hayward but have had no luck. I'm thinking it could be the board. If I pull the igniter off the board I get a 120 volts when it first tries, but then will throw the IO code immediately and stop trying because it's unplugged. With the igniter plugged in the voltage fluctuates between 88 and 105 when it is trying to start, ie for about the 10 seconds when it powers the igniter. Under load would it be normal to see this voltage drop vs. unplugged? I've never seen this before in other types of applications. Any thoughts from someone that has more experience than I do?