The reductant pressure sensor is a component of the AdBlue system in diesel engines. AdBlue is a liquid solution of urea and water that is injected into the exhaust stream to reduce the emissions of nitrogen oxides (NOx). The reductant pressure sensor monitors the pressure of the AdBlue fluid in the reductant pump and sensor assembly, and sends a signal to the reductant control module. The reductant control module uses this information to adjust the amount and timing of the AdBlue injection, as well as to detect any faults or leaks in the system.
The reductant pressure sensor is located in the reductant pump and sensor assembly, which is mounted on the AdBlue tank under the vehicle. The reductant pump and sensor assembly consists of a pump, a pressure sensor, a temperature sensor, a heater, and a filter. The reductant pump and sensor assembly is connected to the AdBlue injector by a high-pressure line. The reductant pressure sensor is a three-wire sensor that has a 5-volt reference, a ground, and a signal circuit.
The reductant pressure sensor measures the pressure of the AdBlue fluid in the reductant pump and sensor assembly, and converts it into a voltage signal that ranges from 0.5 to 4.5 volts. The signal voltage increases as the pressure increases, and decreases as the pressure decreases. The reductant control module monitors the signal voltage and compares it to a desired pressure value, which varies depending on the engine operating conditions and the ambient temperature. The reductant control module controls the reductant pump to maintain the desired pressure, and also controls the reductant injector to deliver the appropriate amount of AdBlue into the exhaust stream. The reductant pressure sensor also helps the reductant control module to detect any faults or leaks in the AdBlue system, such as low fluid level, low pressure, high pressure, or open or short circuits. If a fault is detected, the reductant control module will store a diagnostic trouble code (DTC) and illuminate the check engine light or the AdBlue warning light.