What is a car scan report?
How a scan works
Modern cars store diagnostic trouble codes in their computers. A scanner plugged into the diagnostic port reads those codes and often shows readiness monitors, which indicate whether emissions systems have completed their self-checks.
A clean scan does not guarantee a healthy car, since some problems do not trigger codes. Use the report as one piece of your inspection, not the whole picture.
- Reads stored trouble codes
- Shows readiness monitor status
- Can reveal cleared codes
- Does not catch every mechanical fault
Using the report wisely
Look for recently cleared codes or monitors that show not ready, since a seller may have cleared codes just before a sale. Ask the seller why a code appeared if one shows up.
A mechanic can run a more detailed scan and check live data, which is worth paying for before a larger purchase.
Ask the seller to be present during the scan if possible, and take a photo of the report. That gives you a record to compare with a later scan or with the mechanic's findings, and it shows you what was checked on the day of the sale.
Common mistakes
- Treating a clean scan as proof the car is in good shape.
- Ignoring cleared codes or monitors that are not ready.
- Using a cheap scanner's results without checking them against a professional scan.
