THE BEECHMONT CREST AUTOMOTIVE LEARNING ZONE
OBD II System
On-board diagnostics generation II system. All modern vehicles are equipped with a computerized diagnostic system that monitors vehicle operation. OBD II systems also detect problems that negatively effect vehicle emissions. When the OBD II system detects a problem, it illuminates a dashboard light and stores a trouble code. (This code must be read by a qualified technician using a special scan tool.) OBD II systems can produce hundreds of trouble codes related to specific problems.
Earlier diagnostic systems (OBD I, or on-board diagnostics generation I) illuminated a dashboard light and stored a code only when a sensor or circuit failed completely. OBD II systems are considerably more sensitive. In addition to a sensor/circuit failure, they can also detect the deterioration of parts, or points where specific operations have become less efficient.
The lights that the OBD II system illuminates are called MILs, or malfunction indicator lights. If an MIL glows continuously, the car should be checked at the owner’s convenience, but it is still safe to drive. However, a flashing MIL indicates a serious problem that should be checked immediately.