Why Is My Freightliner Smoking? This can be caused by multiple things. One simple reason that this could happen is a plugged air filter. A plugged air filter would not allow the engine to get enough air for fuel that is injected into the cylinder. On a late model Freightliner Truck with a DPF & SCR system on the truck you won’t see the black smoke. What you will notice is that your Freightliner Truck will be doing more Regeneration Events. Therefore, Maintenance on your Freightliner is important. Air and Fuel Filters need to be replaced on scheduled maintenance times so that these filters don’t get a chance to cause an issue. If your Freightliner Truck is in a Derate Mode, you need Detroit Diagnostic Link to be able to fix the problem correctly. We have the Detroit Engine Software to be able to Diagnose Your Check Engine Light. If you have a late Model Freightliner truck and can see smoke coming from the stacks, it’s possible that you have a cracked DPF Filter. We have the equipment to Diagnose and Replace the DPF filter if needed. We can also take care of all your Engine and Transmission rebuild needs. We also have the electrical If you are experiencing a Why Is My Freightliner Smoking give us a call and we would be happy Diagnose the problem for you.