Hello and welcome to just answer Dodge. Your 6.7L Cummins engine has a sophisticated emission system (so does Ford ands GM diesels). This includer a Diesel Particulate Filter (DPF) that is mounted towards the rear of the exhaust system. This filter traps and burns off the soot that is produced during the diesel combustion process. If the soot in the DPF accumulates too much, then this message will be displayed telling you that you need to take action. Normally the system will burn off this soot while driving. If you do a lot of in town stop and go driving, then this rebenerating soot burning process may not be enough to remove/burn off the soot. You will need to take thge truck to your dealer and they will force the regen process and clean out the soot. They will also check your software level in the truck's ECM (engine computer) and update it if necessary. This should be covered under your Cummins warranty with no expense to you. Get your truck to the dealker asap, because if it plugs up too much, then the engine will not run.
Hope this information helps, and let me know if you need more assistance with this,
the truck is out of warranty and i do not live near a dealer you told me what the owners
Ok, I did not know if you knew anything about this system so I like to be as thorough as possible in my answers. If you do not live near a dealer then do this: remove the DPF and use a pressure washer to clean out the DPF. (use warm water if you can). Reinstall the DPF and then drive the truck at 55 to 65 mph for about 45 minutes or so. This should allow the engine to regen and finish cleaning up the DPF.