Diesel Exhaust System Sensors — General Information (Peugeot Eurovans 807)

Sensors are installed on the intake pipe before the catalytic converter and after the particulate filter, measuring the exhaust gas temperature at the inlet and outlet. Both sensors are resistors whose resistance changes with temperature, or, in other words, have a negative temperature coefficient (see illustration 5.0). At an exhaust gas temperature of 100°, the sensor and resistance are 96,000 Ohms, and at a temperature of 450°C - 762 Ohms. Information from both sensors is used by the engine control unit to monitor the fuel system.



In addition to the sensors listed above, the exhaust system also contains an exhaust gas pressure sensor that records the difference between the exhaust gas pressure at the inlet to the catalytic converter and at the outlet of the particulate filter. Based on the signals from this sensor, the engine control unit determines the condition of the particulate filter and the need to clean it (see illustrations 5.0a, 5.0b).







The sensor's signal is interpreted as the difference in pressure exerted on the diaphragm by the incoming and outgoing exhaust gas flows. If the potential difference is 0 bar with an output signal voltage of 0.5 V, the control unit interprets this as information indicating the filter is clean. At a pressure difference of 0.9 bar and an output signal voltage of 4.1 V, the unit registers clogging of the particulate filter. Signals are sent to the engine control unit via a three-pin connector from pin 1. Pin 2 is the ground (-) connection, and pin 3 is the 5V supply terminal to the sensor.