1. A method for detecting sensor failure in an oil and gas production system, characterized in that it by means of a process model generates an expected value for one (or more) sensor measurement(s), said expected value being compared with one (or more) actual sensor measurement(s), thereby verifying the validity of the one (or more) actual sensor measurement(s) or indicating the failure of the sensor(s) giving the one (or more) actual sensor measurement(s).