Patent ID: 7028467

Claim:
A method for correcting measured differential pressure across a diesel particulate filter disposed in an exhaust passage of an internal combustion engine to determine when to oxidize particulates accumulated in the diesel particulate filter, said method comprising: estimating temperature of a pressure sensor disposed to measure said differential pressure; acquiring pressure sensor correction factor information by reading output from the pressure sensor and estimated pressure sensor temperature when the engine is not running, determining offset correction factors for the pressure sensor, the offset errors being the difference between the output from the pressure sensor and an output from the pressure sensor at the time when the pressure is zero, which should be constant irrespective of temperature changes; storing relationships between the offset correction factors and temperatures of the pressure sensor; reading the output from the pressure sensor and its estimated temperature when the engine is running for measuring a differential pressure across the diesel particulate filter; determining an offset correction factor based on said acquired information which corresponds to the estimated temperature; and correcting the output of the pressure sensor with the determined offset correction factor.