In the past decade the Environmental Protection Agency (EPA) has made huge strides in trying to control the pollution emitted by diesel engines by integrating emission control devices such as Exhaust Gas Re-circulation (EGR), Selective Catalytic Reduction (SCR) and Diesel Particulate Filters (DPF).
Many diesel vehicle drivers do not care for emission controlling devices as they are failure prone, expensive, and reduce a vehicles capable power. For years many individuals have gotten around these devices by “deleting” them. Deleting them basically renders them useless allowing the bad pollutants back in the air.
The EPA mandated fines if caught with a “delete” done on a truck that operated on highways in any state in the US. Generally these fines aren’t strictly enforced yet, but I think they will be more heavily enforced in the coming years. One of the huge drawbacks to “deleting” is the possibility of a dealership turning away a vehicle for warranty work because a “delete” was done to it.