@Roman garibay, To the first question by Roman, a smog check test and repair is a little different from a test only as more equipment is required. A test only station is require to have a smog dyno, egr teater, timing gun, evap machine tester, books for emission equipment, and a few more simple small items.
How long do you need to drive to reset check engine light? Replaced the upstream O2 sensor on a 1999 Ford Ranger 3.0 flexfuel and the check engine light went off and came back on after driving approx. 4 miles.