Over the time the exhaust gas recirculation (EGR) system may become plugged with debris, the oxygen sensor may also be getting slow or 'lazy' around this time. When servicing or cleaning the EGR system, it is a good idea to replace the oxygen sensor because it works in tandem with the EGR system.
Replace Oxygen Sensor When Servicing EGR System on Toyota RAV4
3 people reported this problem
Yes I had the oxygen sensor replaced last year trying to get the check engine light off and state emission test passed