We present new electron-paramagnetic-resonance (EPR) data on the HEI4/SI5 center in 4H-SiC. So far, the SI5 (SI-5) center has been observed only in as-grown SiC substrates; however, we found that it can be created by electron irradiation to commercial n-type 4H-SiC. The artificially created SI5 center, which we had preliminary called HEI4, was found to be identical with the SI5 center in as-grown SiC. A high-intensity HEI4/SI5 spectrum of irradiated SiC revealed clear hyperfine structures of 29Si and 13C, which enabled us to identify the origin of this center as a carbon antisite-vacancy pair in the negative charge state (CSi-VC –). We assessed its electronic levels using photo-EPR.