Where to get a free check engine light scan
AutoZone, O’Reilly Auto Parts and most Advance Auto Parts stores offer free check engine code scans in the US. Call the store with your year, make and model before you go.
What to ask for at the store
Ask for Fix Finder at AutoZone, VeriScan at O’Reilly or ReliaScan at Advance Auto Parts. Tell the store which warning light you’re seeing. A store may be able to read the check engine code on your car while a separate ABS or transmission warning needs a scan tool that can reach that module.
If the light is flashing
If the light starts flashing while you’re driving, ease off and pull over somewhere safe. Check your owner’s manual. Arrange roadside help if the light keeps flashing or the car is shaking or losing power.
Get a copy of the actual codes
Ask for a printout or take a picture of the report. Save every code exactly as it appears, plus any status the tool shows, such as pending or stored. If the scan includes a freeze frame, keep that too. Tell the shop whether the light first came on after a fill-up, on a cold start or while you were accelerating.
When it’s worth paying for a diagnosis
A scan can show that the fuel vapor system failed a test, for example. The report may suggest a gas cap, but a leak elsewhere can set the same code. If the suggested part is expensive, the car is running poorly or the light keeps coming back, ask the shop what test will confirm the cause and what that test costs.