Methods and systems for an engine system including an exhaust gas sensor are disclosed. In one example, under a first engine fueling condition, an air-fuel ratio correction factor is determined based on an expected air-fuel ratio and an actual air-fuel ratio. During a second engine fueling condition and a third engine non-fueling condition, fuel alcohol content and ambient humidity, respectively, are determined based on the exhaust gas sensor and corrected based on the air-fuel ratio correction factor.