![]() ![]() ![]() ![]() Unlike earlier OBD systems that only set a diagnostic trouble code (DTC) when a sensor circuit experienced a gross failure such as a short, open or over voltage, OBD II sets codes if a fault has the potential of causing emissions to rise. OBD II is primarily emissions-driven and will set codes anytime vehicle emissions exceed the federal limit by 1.5 times. It also will set codes if there is a gross sensor failure, but some types of sensor problems will not always trigger a code. Consequently, the Check Engine Light on an OBD II-equipped vehicle may come on when there is no apparent drivability problem, or it may not come on even though a vehicle is experiencing a noticeable drivability problem. The determining factor as to whether or not the Check Engine light comes on is usually the effect on emissions. In many instances, emissions can be held in check, despite a faulty sensor, by adjusting fuel trim, which the engine computer does automatically. So as long as emissions remain under the legal limit, the Check Engine Light usually remains off. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |