In California regardless of a vehicle's age, the check engine light is inspected if the vehicle is equipped with one. The difference between an older model Volvo (1995 and older) and a newer model is that on a 1996 and newer vehicle the engine's computer relays check engine light data to the smog machine via the OBD II data link connector. On older OBD I models there is no data link connector. The technician visually observes the check engine light for illumination and enters this information on the smog machine. Subsequently a vehicle with its check engine light fails the smog test.
