When the DTC P2000 OBDII code is stored, it means that the vehicle’s computer detects a level of nitric oxide (NOx) above the allowable range.
In internal combustion engines, NOx is produced as an exhaust emission. To reduce these emissions, a catalytic converter (TWC) is used, but taking into account that the TWC is not as effective in gas-burning engines, a NOx trap or NOx absorption system is used. This process is known as the Selective Catalytic Reduction (SCR) system.
In the SCR system, Nitrogen Oxide (NOx) sensors are used in the same way as Oxygen (O2) sensors in gasoline engines. They monitor the NOx particles. In turn, the PCM (Powertrain Control Module) relies on the NOx Sensor and Catalyst data to calculate the NOx trap efficiency.