Optically addressable paramagnetic defects in silicon carbide (SiC) are attractive for scalable quantum technologies such as quantum sensing. PL5, PL6, and PL7 are promising defects for their high brightness and spin-readout contrast. Although generation by oxygen implantation has been reported very recently, nonuniform spin and optical properties and the limited generation depth of implanted defects hinder both high-sensitivity sensing and conclusive microscopic identification. Here we engineer high-quality defects by decoupling oxygen incorporation and defect formation, realizing highly homogeneous spin-resonance frequencies as well as narrow optical linewidths and long T2* coherence time. Further, we demonstrate defect formation beyond the ion range utilizing oxygen diffusion, exceptional among impurities in SiC. We further provide hyperfine-interaction statistics of 17O and host nuclei across many PL6 defects, making the oxygen-vacancy origin conclusive. Together, the microscopic identification and the demonstrated formation route establish a foundation for developing the oxygen-vacancy spin defect into a versatile quantum platform.