EGR Systems (Exhaust Gas Recirculation) significantly reduce the pollutants produced by the engine. However, since diesel engines produce a higher amount of emissions, the SCR System (Selective Catalytic Reduction) was also implemented in these engines. The latter injects Diesel Exhaust Fluid through a solenoid valve, a process that increases the temperature of the Diesel Particulate Filter to achieve better performance and a reduction in the release of emissions.
A booster supply pump is located in this system, which allows the Diesel Exhaust Fluid to be pressurized when necessary. The PCM monitors the voltage supply to this pump to check that there is consistency in voltage delivery, as well as an adequate charge level. The PCM also monitors one or more pressure sensors to determine if there are any leaks in the system.
If the Powertrain Control Module finds a voltage level in the Reducer Tank Temperature Sensor circuit that shows performance problems in the circuit, it will set the P205B OBDII fault code.