The Public & OBD II

The odds are that most owners will never know their car has an OBD II system unless the MIL comes on. At that point, it will probably be someone in the service department who will be called upon to explain it to them. Every person in the dealership who comes in contact with the consumer should be familiar with basic OBD II concepts and be able to explain how the MIL is controlled. A few of the important changes to MIL operation for 1996 are listed below:

^ Most importantly, there are a great many more "problems" capable of turning on the light. Some of these, such as a 900 EVAP system leak caused by a forgotten gas cap, scarcely install the traditional concept of a failure.

^ The chain of events which will turn on the light can be quite complex. With OBD I the MIL came on as soon as the fault was detected. With OBD II many of the faults must occur two times before the light will come on, these occurrences may be days or even weeks apart.

^ With intermittent problems, OBD I would turn on the MIL as soon as a fault was detected but would turn the light off the next time you cycled the key if the fault was no longer there. Under similar circumstances, an OBD II system will leave the light on much longer, conceivably for days. The system is designed to make sure that the customer is aware of any problems and provide the motivation to get them fixed.