A method of monitoring a functional state of an electricity meter, includes generating at least one temperature signal from which an actual temperature value of the electricity meter can be derived; determining whether the actual temperature value and/or a gradient thereof exceeds at least one threshold value derived from at least one predefined temperature curve representing predefined temperature values of the electricity meter over time according to a modelled thermal behaviour of the electricity meter. Further, a computer program, a computer-readable data carrier having stored thereon a computer program, a data carrier signal carrying a computer program, and an electricity meter configured to carry out the computer program are described. Finally, an electricity metering system, in particular an Advanced Metering Infrastructure, includes at least one electricity meter and/or at least one administration device configured to carry out a method of monitoring a functional state of an electricity meter.