Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Trouble Codes With Test Charts (6-Cylinder): Introduction: Notes
If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES , proceed with self-diagnostics. BMW vehicles are equipped with an OBD-II self-diagnostic system for accessing Diagnostic Trouble Codes (DTC) using a generic scan tool connected to vehicle Data Link Connector (DLC). See Fig 1-Fig 2 . BMW trouble codes can be accessed using BMW's Diagnostic Information System (DIS) or Mobile Diagnostic Computer (MoDiC).
DME/Motronic/Siemens control unit provides a substitute value if a failure occurs in an engine performance related component, such as engine (coolant) temperature sensor, intake air temperature sensor, airflow meter or exhaust gas oxygen sensor. See ENGINE MANAGEMENT SYSTEM IDENTIFICATION table. These substitute values are canceled when normal engine operation is resumed.
If no DTCs are present after entering self-diagnostics, proceed to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.