Air-fuel ratio controller of internal combustion engine

摘要

The invention relates to an air-fuel (A/F) ratio controller of an internal combustion engine, which is provided with a constant-voltage circuit between the heater for heating the A/F ratio sensor and the power-supply source. Regardless of variation of voltage outputted from the power-supply source, the A/F ratio controller securely maintains the heater voltage constant and prevents occurrence of error in the signal outputted from the A/F ratio sensor by correctly operating the oxygen-concentration detecting element whose measuring precision is solely dependent on temperature.