Out of the several factors responsible for processor power dissipation, the branch prediction unit itself contributes to almost 10% of the overall processor power dissipation. The functioning of predictors is, therefore, to be more accurate especially for the CMPs (chip multiprocessors) with thousands of on-chip cores. This work reports that the design inaccuracy (fault) in a predictor can cause a huge power loss, even up to95%. The impact of faults causing additional loss in processor power is estimated to diagnose the faulty module of a predictor. This has been established through introduction of probable faults/design inaccuracies to each of the functional modules of a predictor. Exhaustive experimentations on the state-of-the-art predictors reveal that the amount of additional power loss during processor execution clearly points to the specific design inaccuracies. This effectively leads to identification of the faulty module of a predictor.