Air pump abnormality-detecting system for internal combustion engines

Abstract

An air pump abnormality-detecting system for an internal combustion engine. The engine has a catalyst arranged in the exhaust system of the engine, a passage extending from the exhaust system at a location upstream of the catalyst, and an electrically driven air pump arranged across the passage, for supplying secondary air into the exhaust system. A current sensor detects electric current flowing through the air pump, and a voltage sensor detects voltage applied to the air pump. An abnormality of the air pump is detected by comparing an output from the current sensor obtained during operation of the air pump, with predetermined abnormality-detecting reference values. At least one of the output from the current sensor or the predetermined abnormality-detecting reference values is corrected in response to an output from the voltage sensor.