A process variable transmitter, comprising: a sensor (22, 24) configured to sense a process variable and to provide sensor values indicative of a sensed process variable; a memory; a processor configured to receive the sensor values from the sensor (22, 24), wherein the processor comprises a sensor deviation detector configured to: - calculate a rate-of-change estimate of the sensor signal based on a difference between one of the received sensor values and an average of a number of previously received sensor values from the sensor (22, 24) which is stored in the memory; - calculate a deviation value based on an absolute value of a difference between the calculated rate-of-change estimate and an average of a number of previously calculated rate-of-change estimates which is stored in the memory; and if the calculated deviation value exceeds or surpasses a threshold value: - generate an output indication; and, if the calculated deviation value does not surpass the threshold value: - update the average of the number of previously received sensor values and the average of the number of previously calculated rate-of-change estimates and store them in the memory. a sensor (22, 24) configured to sense a process variable and to provide sensor values indicative of a sensed process variable; a memory; a processor configured to receive the sensor values from the sensor (22, 24), wherein the processor comprises a sensor deviation detector configured to: - calculate a rate-of-change estimate of the sensor signal based on a difference between one of the received sensor values and an average of a number of previously received sensor values from the sensor (22, 24) which is stored in the memory; - calculate a deviation value based on an absolute value of a difference between the calculated rate-of-change estimate and an average of a number of previously calculated rate-of-change estimates which is stored in the memory; and if the calculated deviation value exceeds or surpasses a threshold value: - generate an output indication; and, if the calculated deviation value does not surpass the threshold value: - update the average of the number of previously received sensor values and the average of the number of previously calculated rate-of-change estimates and store them in the memory. receive the sensor values from the sensor (22, 24), wherein the processor comprises a sensor deviation detector configured to: - calculate a rate-of-change estimate of the sensor signal based on a difference between one of the received sensor values and an average of a number of previously received sensor values from the sensor (22, 24) which is stored in the memory; - calculate a deviation value based on an absolute value of a difference between the calculated rate-of-change estimate and an average of a number of previously calculated rate-of-change estimates which is stored in the memory; and if the calculated deviation value exceeds or surpasses a threshold value: - generate an output indication; and, - calculate a rate-of-change estimate of the sensor signal based on a difference between one of the received sensor values and an average of a number of previously received sensor values from the sensor (22, 24) which is stored in the memory; - calculate a deviation value based on an absolute value of a difference between the calculated rate-of-change estimate and an average of a number of previously calculated rate-of-change estimates which is stored in the memory; and if the calculated deviation value exceeds or surpasses a threshold value: - generate an output indication; and, if the calculated deviation value does not surpass the threshold value: - update the average of the number of previously received sensor values and the average of the number of previously calculated rate-of-change estimates and store them in the memory. - update the average of the number of previously received sensor values and the average of the number of previously calculated rate-of-change estimates and store them in the memory.