What is OBD-II?

OBD-II stands for On-Board Diagnostics II. It is the standard system vehicles use to monitor engine, emissions and other key systems and store fault codes when a problem is detected.

When a sensor reading or control function goes outside the expected range, the system stores a diagnostic trouble code and may turn on the engine management light.

OBD-II codes help point you to the area of concern, but proper diagnosis is still needed to confirm the exact cause.