An ECU performs exhaust temperature control based on output values of multiple exhaust temperature sensors provided upstream and downstream of a particulate filter provided in an exhaust passage of an engine. The ECU calculates a change speed deviation value by subtracting change speed of outlet side exhaust temperature, which is sensed by one of the exhaust temperature sensors, from change speed of inlet side exhaust temperature, which is sensed by the other one of the exhaust temperature sensors, in an operation state in which temperature of exhaust gas flowing through the particulate filter changes rapidly. The ECU determines that the exhaust temperature sensors are mounted erroneously if the change speed deviation value deviates from a predetermined normal range.