An integrated circuit precharges a node 6 to a precharge voltage using precharging circuitry 4. During a discharge phase discharging circuitry 8 selectively discharges that node 6 is to represent a data/signal value. Sensing circuitry 10 detects a discharge characteristic to identify the data/signal value being represented. During the subsequent precharging operation of the node 6 back to the precharge voltage, validating circuitry 12 detects a precharge characteristic, such as the precharge current, the charge transferred, changes in the node voltage or a like, and compares this to the detected discharge characteristic corresponding to the data/signal value sensed by the sensing circuitry. If there is a mismatch, then an operation error signal is generated. The operation error signal may be used to adjust operation parameter, such as the operating voltage/frequency, the timing of the operation of a portion of the integrated circuit or another parameter.