Oxygen Sensors

OXYGEN SENSORS
Four oxygen sensors are used on the MS S52 as with other engine management systems. Two oxygen sensors, mounted in front of the catalytic converters and two sensors are mounted behind the converters to monitor the efficiency of the catalyst.

The two pre-converter oxygen sensors monitor the air fuel mixture and their inputs are used to adjust the mixture to achieve the ideal air/fuel ratio for all driving conditions. When heated, the oxygen sensor generates a voltage based on the oxygen content differential between the exhaust gas and the ambient air. The greater the oxygen differential, the higher the voltage generated will be. The oxygen sensor swing in voltage ranges from 0.15 V (Lean) to 0.85 V (Rich).

The two post-converter oxygen sensors monitor the oxygen level after the conversion by the catalyst. This signal is relatively steady at approximately 0.8 V. The engine control module compares the signals of the pre and post oxygen sensors for conversion efficiency and if the values go outside of the programmed parameters, faults will be stored relating to catalytic converter operation.