VEHICLE

A vehicle includes an engine, an exhaust flow passage, an air-fuel ratio sensor, and a control apparatus. The exhaust flow passage is configured to communicate with the engine. The air-fuel ratio sensor is provided in the exhaust flow passage. The control apparatus includes one or more processors, and one or more memories coupled to the one or more processors. The one or more processors are configured to: cause backflow of gas inside the exhaust flow passage while the vehicle is stopped; and diagnose a state of adhesion of oil inside the exhaust flow passage, based on a result of detection performed by the air-fuel ratio sensor in causing the backflow of the gas inside the exhaust flow passage.