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How to Use an OBD-II Scanner
An OBD-II scanner is a clue finder. It can point you toward a system, but it does not prove which part has failed by itself.
Basic Steps
- Find the OBD-II port, usually under the dashboard on the driver's side.
- Plug in the scanner with the ignition off, then follow the scanner instructions.
- Read stored, pending, and permanent codes before clearing anything.
- Write down codes exactly, including letters and numbers.
What To Record
- The code number and description.
- Freeze-frame data if your scanner shows it.
- Whether the check engine light is steady or flashing.
- The symptoms you felt when the light appeared.
Common Mistakes
- Do not replace a part only because its name appears in a code.
- Do not clear codes before inspection if the problem is still active.
- Do not ignore symptoms just because no code appears.