Where the port is and how a code reader connects.
The short version of how reading a Check Engine code actually works.
Where the OBD2 port is
Cars and light trucks sold in the United States since model year 1996 have a standard 16-pin OBD2 port. It is usually under the dashboard on the driver’s side, often near the steering column or above the pedals. Check your owner’s manual if you cannot spot it.
How to read a code
- Park safely. Turn the ignition off.
- Plug the reader into the port.
- Turn the ignition on (engine on or off, as the reader’s instructions say).
- Follow the reader or phone app to read stored codes and write them down.
- Look up what each code means, starting with the simple checks.
Phone-based readers
Bluetooth readers have no screen. They pair with an app on your phone or tablet, which means your phone must be charged and the app must work with your vehicle. Check the seller’s compatibility information before you buy.
Be careful with clearing codes
Clearing codes turns the light off but does not fix the cause, which usually brings the light back. It also resets the car’s emissions readiness monitors, which may take days of normal driving to complete. A car that is not “ready” can be rejected at an emissions test. Do not clear codes just before a test.
When to stop and call a professional
- The Check Engine light is flashing.
- An oil-pressure or temperature warning is on.
- The engine runs rough or loses power.
- You smell fuel.
See the Disclaimer. Back to the Check Engine guide.