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.
On Board Diagnostics II: Notes
In parallel with the Low Emission Vehicle program, the ARB developed and mandated OBD II. OBD II as we are aware, requires that all vehicle manufacturers comply with extensive fault monitoring capabilities for all emission related drivetrain control systems.
These systems; DME, AGS and EML must monitor their components electrically and monitor for plausible mechanical engine function. Additionally, OBD II provides a separate Diagnostic Link Connector (DLC) located in the vehicle interior to access OBD II fault codes with an aftermarket scan tool.
BMW center technicians have the advantage of utilizing BMW diagnostic equipment and software (DIS/MoDiC) to interface with all vehicle control systems. However, understanding how OBD II compliance has changed engine mechanical hardware and control system monitoring capabilities should be understood by all BMW center technicians.
All U.S. market BMW vehicles have been OBD II compliant since the 1996 model year.
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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.