Both Riverside County and San Diego County belong to California's Enhanced Emissions Test Program area. You may obtain a smog check for your vehicle in either county. Only consideration should be given to the type of smog test required by the DMV; STAR or Non-STAR.
If there is no mention of a STAR smog check requirement on your registration renewal document, you may obtain your smog check at any smog test certified smog station. If your renewal paper requests a STAR certified smog test, you must ensure the smog station which inspects your vehicle is STAR certified by the Bureau of Automotive Repairs.
Read more... What is a STAR Smog Test?
