Method for monitoring the condition of a measurement sensor

A method for monitoring a condition of a measurement sensor for detecting the density or mass flow rate of a medium, said measurement sensor being installed at a measuring point and comprising at least one oscillator excited to oscillate, which has at least one measuring tube for conveying the medium, wherein a condition parameter of the condition is dependent upon at least one further physical parameter of the medium conveyed in the measuring tube or of the oscillator;

• wherein the method comprises:
• determining tuples which contain a value of the at least one physical parameter and an associated value of the condition parameter;
• assigning the tuples in each case to a value range of the at least one physical parameter;
• and
• forming a reference value of the condition parameter for this value range of the at least one physical parameter using the value of the condition parameter of the tuple when no valid reference value of the condition parameter for this value range is present;
• or
• comparing the value of the condition parameter of the tuple with the reference value when a reference value of the condition parameter for this value range is present;
• and generating a finding on the basis of the result of the comparison.