The purpose of the scientific work is to develop a software implementation, to study the algorithm for finding errors in modular codes (MC) and their detection by introducing two redundant moduli. The study focuses on the characteristics of errors that occur in the codes of the residue number system (RNS), without the direct purpose of detecting them. To conduct the study, an approach based on the calculation of all entered allowed combinations of the code of the RNS was taken as a basis, followed by obtaining intervals without taking into account rank. To achieve this goal, a program code in the C++ language was developed, which includes a menu with functions for searching for a single error in modular codes. The presented approach and software implementation can be useful to specialists in the field of information systems of transmission and signal processing in the analysis and correction of errors in modular codes.