A generic OBD2 code reader will only read emissions-related codes. To diagnose issues specific to BMW vehicles, you need a scan tool that can read BMW manufacturer codes. This is crucial for preventative maintenance and accurate diagnostics.
A prime example of why a BMW specific scan tool is essential is the water pump. When a BMW water pump begins to fail, it will intermittently slow down. BMW engineered their diagnostics system to log specific codes indicating these slow pump speeds, recording mileage and RPM deviation. These codes allow for preemptive replacement before total failure and potential overheating. Since the E9X series lacks a traditional water temperature gauge, relying solely on an OBD2 reader could lead to undetected problems.
Unlike generic OBD2 readers, a BMW specific scan tool, such as the BT Scan Tool Professional, can access all modules in the car (e.g., engine, transmission, ABS) and retrieve all fault codes within each. This comprehensive diagnostic capability allows you to identify issues beyond the scope of the basic emissions control system covered by OBD2. For example, you can diagnose problems with the automatic transmission, a system not covered by standard OBD2 protocols. Remember, OBDII is a US government mandated standard focusing solely on emissions, limiting its diagnostic scope for BMW specific issues. Therefore, to properly diagnose and maintain a BMW, invest in a scan tool capable of reading BMW manufacturer specific codes.
