A method and system for identification and reduction of an air-fuel ratio imbalance

There are provided methods and systems for identifying an unbalanced cylinder and mitigating the unbalanced cylinder. In one example, a method may include identifying an unbalanced cylinder on the basis of measured values ​​of two exhaust gas oxygen sensors positioned upstream and downstream of a catalyst in an exhaust conduit, and mitigating the unbalance on the basis of the extent of an error that has been determined from the measured values, include.