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Oxygen Sensors

The oxygen sensor is downstream of the catalytic converter in the exhaust gas stream where it measures the remaining oxygen content of the exhaust emissions and informs the ECU (engine control unit) accordingly. The installation position of the oxygen sensor varies depending on make and model and whether the car’s exhaust system is a V-type or in-line engine model. Many new car models have a second oxygen sensor behind the catalytic converter in addition to the one in front of it. The oxygen sensor in front of the catalytic converter is a control sensor that supports the ECU with the regulation of the fuel-air mixture composition in a closed loop configuration. The oxygen sensor after the catalytic converter is a diagnostic sensor which monitors the efficiency of the converter.

Finger-type sensor

The finger-type sensor contains a finger-shaped sensor ceramic as core piece. It is provided with a separate heater, since an operation temperature that starts at 350 °C is required for accurate control loop functionality. The sensor housing is fitted with a guard tube in order to protect the sensor element against combustion residue in the exhaust gas.

Planar sensor

The planar oxygen sensor is a more advanced form of the finger-type sensor. The sensor element has the shape of an elongated plate. In order to attain its operating state more quickly, the heater is integrated into this plate in addition to the measurement cell.

Wideband sensor

Another type of oxygen sensor is the wideband sensor, also called UEGO sensor (Universal Exhaust Gas Oxygen). These sensors are used for lean burn petrol engines as five-pole control loop sensors. The wideband sensor is able to send out a proportional output signal, depending on the air fuel mixture and the oxygen content of the exhaust gas. This ensures extremely accurate measurement for both the rich and the lean mixture conditions.

BBT-Oxygen Sensor