When picking a tool to assist in the electrical troubleshooting of your BMW or Mini vehicle, it becomes important to note the two important differences between the generic "OBD-II" type devices and those which are designed to read out the BMW factory fault codes.
First, it is important to realize that the OBD-II codes were designed specifically for EMISSIONS RELATED FAULTS, and that many other possible faults in your BMW are not readable under the OBD-II protocol.
|
An example scenario would be that your E36 328i or M3 isn't starting. An OBD-II code tool might show "no faults" whereas a BMW specific tool might show code D1 (hex) or 209 (decimal) indicating an EWS code problem. The EWS code problem is not considered "EMISSIONS RELATED" and hence there is no OBD-II code indicated. This of course does nothing to start the car. |
A cursory scan of BMW faults vs OBD-II faults for the E36 328 shows that 28 BMW codes are NOT REPRESENTED as OBD-II faults. Numbers of codes that are similarly not represented exist for every BMW that I have examined.
Next, it is important to realize that the OBD-II codes are less specific than BMW's proprietary codes for the simple fact that there is NOT a consistent 1 to 1 relationship between BMW codes and OBD-II codes.
On the E36 M3, OBD-II codes 0440, 0441, and 0442 each indicate "one of two" BMW specific codes. Similar duplicity exists in every BMW examined
The reason for this becomes clear when you remember that BMW designed the fault codes to assist the technician in diagnosing and repairing your car.
 |
The OBD-II fault codes were government-mandated designed for EMISSIONS diagnosis. |
|
OBDII tools can not reset the oilservice and inspection maintenance reminder lights. |
|
OBDII tools will not work on BMWs built before 1996. |
|
OBDII tools will not read or reset BMW airbag. |