An industrial process field device for sensing a process variable comprising: a piezoelectric transducer ; a sensor circuit configured to operate the piezoelectric transducer in a sensing mode, in which the sensor circuit generates a sensor signal indicating the process variable based on a voltage across the piezoelectric transducer ; a test circuit configured to operate the piezoelectric transducer in a testing mode, in which the test circuit : applies a voltage pulse having a pulse voltage to the piezoelectric transducer that deforms the piezoelectric transducer and induces a response signal from the piezoelectric transducer ; captures a peak positive voltage of the response signal; and captures a peak negative voltage of the response signal; a memory ; a controller configured to: store the captured peak positive voltage of the response signal in the memory ; store the captured peak negative voltage of the response signal in the memory ; calculate a current condition value of the piezoelectric transducer based on a ratio of the sum of the absolute values of the peak positive voltage and the peak negative voltage to the pulse voltage ; and generate a diagnostic test result based on a comparison of the current condition value to a reference condition value corresponding to a properly operating piezoelectric transducer ; and a communications circuit configured to communicate the process variable and the diagnostic test result to an external control unit over a process control loop . a piezoelectric transducer ; a sensor circuit configured to operate the piezoelectric transducer in a sensing mode, in which the sensor circuit generates a sensor signal indicating the process variable based on a voltage across the piezoelectric transducer ; a test circuit configured to operate the piezoelectric transducer in a testing mode, in which the test circuit : applies a voltage pulse having a pulse voltage to the piezoelectric transducer that deforms the piezoelectric transducer and induces a response signal from the piezoelectric transducer ; captures a peak positive voltage of the response signal; and captures a peak negative voltage of the response signal; applies a voltage pulse having a pulse voltage to the piezoelectric transducer that deforms the piezoelectric transducer and induces a response signal from the piezoelectric transducer ; captures a peak positive voltage of the response signal; and captures a peak negative voltage of the response signal; a memory ; a controller configured to: store the captured peak positive voltage of the response signal in the memory ; store the captured peak negative voltage of the response signal in the memory ; calculate a current condition value of the piezoelectric transducer based on a ratio of the sum of the absolute values of the peak positive voltage and the peak negative voltage to the pulse voltage ; and generate a diagnostic test result based on a comparison of the current condition value to a reference condition value corresponding to a properly operating piezoelectric transducer ; and store the captured peak positive voltage of the response signal in the memory ; store the captured peak negative voltage of the response signal in the memory ; calculate a current condition value of the piezoelectric transducer based on a ratio of the sum of the absolute values of the peak positive voltage and the peak negative voltage to the pulse voltage ; and generate a diagnostic test result based on a comparison of the current condition value to a reference condition value corresponding to a properly operating piezoelectric transducer ; and a communications circuit configured to communicate the process variable and the diagnostic test result to an external control unit over a process control loop . <EOS>