Patent ID: 7614391

Claim:
A correction apparatus for correcting an error in an output of an oxygen sensor installed in an exhaust pipe of an internal combustion engine to measure a concentration of oxygen contained in exhaust gas comprising: a correction factor determining circuit that executes a fuel cut operation to cut a supply of fuel to the internal combustion engine to bring a pressure in the exhaust pipe to an atmospheric pressure when a given running condition of the internal combustion engine is encountered, said correction factor determining circuit entering an under-atmosphere correction mode during the fuel cut operation to sample an output of the oxygen sensor and determining a correction factor which compensates for a deviation of the sampled output from a reference value that represents an actual concentration of oxygen in the exhaust pipe and which is used to correct an output of the oxygen sensor when the internal combustion engine is undergoing no fuel cut; an exhaust gas pressure information deriving circuit that derives information about a pressure of exhaust gas in the exhaust pipe after start of the fuel cut operation; and a correction mode execution determining circuit that determines whether the under-atmosphere correction mode is to be entered or not based on the information about the pressure of exhaust gas.