have hayward 400 hdp model spa heater,,, went to start after running fine 2 days earlier,, heater would not ignite,, goes thru its 3 cycles of trying to light then displays code,, can smell gas so assuming gas pressure not problem,, tested igniter and it works..... have tried doing the 3 cycle start at least 6 times same result,, can hear and tell it is trying to fire but wont ignite heater, researched everywhere only real explanation and posibble fix has been clean unit and injectors that has not fixed please if anyone had same or similar issues,, im desperite not wanting to call tech if something i can do to check on possible problems thx