According to records filed in the case, Achtemeier conspired with mechanics in garages and operators of truck fleets to disable the anti-pollution software installed on diesel trucks.
Coconspirators who wanted to disable their trucks’ pollution control hardware system—a process commonly known as “deleting”—sought Achtemeier’s help to trick the truck’s software into believing the emissions control systems were still functional, a process known as “tuning.”
Monitoring software on a deleted truck will detect that the pollution control hardware is not functioning and will prevent the truck from running. Achtemeier disabled the monitoring software on his client’s trucks by connecting to laptops he had provided to various coconspirators. Some of the coconspirators would pass the laptop on to others seeking to have the anti-pollution software disabled on their trucks. Once the laptop was hooked up to the truck’s onboard computer, Achtemeier could access it from his computer and tune the software designed to slow the truck if the pollution control device was missing or malfunctioning. Achtemeier could “tune” trucks remotely, which enabled him to maximize his environmental impact and personal profit.
When you run out of DEF or the DPF is clogged, you can’t run your truck for more than a brief while. You get half output in a limp-mode to go refill your DEF or have the DPF serviced. DEF is the reactant for the exhaust that makes diesel burn cleaner, but means modern trucks have 2 tanks now. Users hate it, but it cuts emissions massively. Also adds a few grand to the vehicle exhaust system in hardware and sensors and control units. Anyways:
Time = money.
For a commercial or even semi private vehicle if you bypass even one indicent of downtime by doing this is paid for itself.
That said, the DPF is a filter, and can physically clog and cause an exhaust fire if there is no monitoring software. I hope at least this guy had it wait till it was almost critical and then stop, not entirely disable the stop signal. Otherwise there is a serious risk to the vehicle and passengers.