I have a 2001 f-350 7.3 powerstroke with the check engine light on I hooked up a 2500 scanner by snap-on and then I got a code that says I have a high low open on cylinder 4. and I'm not sure what that means the truck use to shake until I put a new fuel filter in it now I just want to know that a high low open on cylinder 4 is and how to fix it?? Can any one help?

What was the actual code that was stored?