Air-fuel ratio detecting device

An air-fuel ratio detecting device, comprising:

• an air-fuel ratio sensor for producing air-fuel ratio information indicative of the concentration of oxygen in an exhaust gas produced by a burned air-fuel mixture in an internal combustion engine, said air-fuel ratio sensor being disposed in an exhaust pipe;
• operating status data detecting means for detecting engine operating parameters indicative of or corresponding to a pressure in the exhaust gas;
• pressure difference calculating means for calculating the pressure difference between a first pressure which acts on said air-fuel ratio sensor to cause the air-fuel ratio sensor to have reference output characteristics when the air-fuel ratio sensor is placed in a reference atmosphere and a second pressure which is indicative of or corresponding to said pressure in the exhaust gas detected by said operating status detecting means;
• and
• air-fuel ratio calculating means for correcting an air-fuel ratio based on said air-fuel ratio information from said air-fuel ratio sensor with the pressure difference calculated by said pressure difference calculating means, for thereby producing a pressure-corrected air-fuel ratio.