We develop a new technique for fault detection based on a new metric, the energy consumption ratio (ECR). ECR-based test can detect faults, such as redundant faults, that escape detection with other techniques. Though the ECR is a metric based on the supply current, an analog parameter, it is remarkably tolerant to the impact of process variations. The quality of ECR-based test is demonstrated through extensive simulation on a process offered by MOSIS. We also present a test generation algorithm for the new test technique. When applied to benchmark circuits, this technique reliably detects a large fraction of the combinationally redundant faults in them.