Technically only Test & Repair or Repair Only certified California smog stations are allowed to diagnose and repair smog check failures, however a ARD license holder not willing to participate in California's smog check program is not restricted from repairing emission components. Just keep in mind that when visiting a non-smog check certified auto repair center, the BAR's smog check enforcement division will not get involved if something goes wrong with emission related repairs. Nor will any money spent on emission related repairs at such an auto repair center go towards your CAP deductible should you choose to apply for State Emission Repair Assistance. With that said... replacing the oxygen sensor on your 1993 Honda Accord is technically a smog check related repair when performed for the purposes of passing the smog check. We recommend contacting the BAR at (800) 952-5210 for more information.