I have a Hayward H400FDN- it has been working fine all summer and a few days ago I started getting the IF error when it tries to light. I have gotten this before, but usually cleaning the inside gas injectors clears up the problem. This problem is different in that the error pops up before the heater can even ignite; it used ignite and fail a few times before id get that message, but now it doesn't even get that far. The internal fan goes in, there are some clicks then comes the error. Today I replaced the ignitor and still no luck. Any ideas? Circuit board maybe?