Hi. Thanks for using JA! I will try and help you out.

This code is indicating the ARD head and or filter fittings are restricted. I see this a lot on these engines. The ARD head will most likely need to be replaced. It is possible to use the cleaner for this but to be honest, the cleaner does not work that often. When it does, The truck always comes back for the same problem within a week. I would recommend replacing the ARD head and filter fittings is the engine has them. Not all C7 engine have filter fittings. To determine if yours does, just follow the fuel lines from the ARD head to the manifold. Remove the fittings from the manifold. If they look like normal fittings, your engine does not have filter filter fittings. If yours has fittings, you will see the screens inside of them .

Please reply back if you need more help.

Please rep;ly back if you need more help.