OBD II - Check Engine Lamp

OBD II - Check Engine Lamp:

The parameters for the Check Engine Lamp illumination are changed for vehicles equipped with the OBD II system. The total scope of OBD 11 monitoring includes all control modules than can influence the amount of exhaust emissions. On the Z3, this includes the engine control module (DME) and if equipped, the automatic transmission control module (TCM).

NOTE: The Transmission control module will have to be considered during troubleshooting when the Check Engine Lamp is illuminated.

Each of these modules monitor any input signals, the processing electronics and or final stage outputs that when defective will cause the level of exhaust emissions to increase above the level that the vehicle was certified to.

The monitoring criteria for each signal or system depends on the degree of influence the signal or output has on the total volume of emissions produced by the engine.

There are specific differences in signal monitoring based on the monitoring time and load on the engine.


Faults that have a severe influence on emission levels will cause the Check Engine Lamp to illuminate immediately.

Other faults may require that the vehicle be driven two times with the fault present before the Check Engine Lamp illuminates.

In all cases the fault will be stored in the respective control module as soon as it is detected.

BASIC TROUBLESHOOTING
- Always personally verify the customer complaint.
- Perform a Quick Test to determine if the vehicle systems have logged fault codes.
- Call up the faulted system or appropriate test schedule to verify the correct control module is installed in the car.
- Follow the Diagnostic Information System (DIS) on screen instructions and perform all tests as specified.
- Use the DIS and fault symptom diagnostic procedures as trained.
- Follow the appropriate test module procedures for systems that malfunction but fail to set faults in memory.
- System problems which elude diagnostic procedures must be brought to the attention of BMW of North America, Inc.