How can you fix the 4 blinks, igniition failure (ground wire)?

I was having the same problem with my heater and it turned out to be the condensate drain trap. If you have your Installation Instructions it was spelled out on page 20 of the one I have here. It gets pluged some times and will cause you light to blink four times. AlsoPressure Switch will send a two blink code. This is spelled out on page 33 of my manual which has the wiring Diagram. Hope this helps.I replaced the switch and then the two blink came on.

Sorry about that but I was looking at the 2 blink code that someone was asking and a question on the 4 blink at the same time. I am still looking for the answer on the four blinks. Mine has a good ground (a cause for the problem). I have heard that a bad ground within the home can cause this code to appear. Haven't had a chance to check that out yet. Again, sorry for the confusion.