It should be a canister on the right side of the engine right about cylinder head height. It’s a cartridge type filter. If you follow the crankcase vent hose from the valve cover it will lead you right to it. There’s a ring at the top that unthreads and the cover will come off. It can be difficult to remove. Generally I see this code on our industrial engines when they are operating at low load during cold weather. You will find the filter covered in white gunk. This code will derate the engine and possibly limit rpm depending on the severity of the code. I would add pictures but I’m hunting today instead of working
I believe if you look in your manual under "Service As Needed" the last line item under that heading should say replace OCV filter. OCV meaning open crankcase ventilation. The later manuals are now showing 1500 hour service interval. In my experience, depending on operation, 1500 hour is too long to keep from tripping the error code.