It is difficult to replace or maintain many plants that were developed in the 1960s, because the original documents of installed sequential control logics are seldom still in existence. Therefore, our research group has proposed a sequential logics automatic regeneration method with an inductive learning algorithm which we have named SPAIR. SPAIR, however, has certain practical problems. Timer error is one of them. In order to solve this problem, we have proposed a timer error correction method. In this method, the average and the dispersion of error are added as timer specifications, and data in an uncertain timer range are not used to learn a target logic that contains timer error. The proposed timer error correction method is shown to be effective in through simulation of a simple tank model.