Methods and systems are provided for estimating an engine exhaust pressure based on outputs from an exhaust oxygen sensor. In one example, a method may include estimating an exhaust pressure of exhaust gas flowing through an engine exhaust passage based on a difference between a first output of an oxygen sensor disposed in the exhaust passage and a second output of the oxygen sensor and then adjusting engine operation based on the estimated exhaust pressure. As one example, both the first and second outputs may be taken while operating the sensor in a variable voltage mode, after increasing a reference voltage of the oxygen sensor from a lower, first voltage to a higher, second voltage.