OBD-II (on-board diagnostics) is a computer system that monitors vehicle systems such as the engine, fuel pumps, exhaust and much more.

When your "check engine" light comes on, it's because the OBD system has detected trouble. And when you take a car in for repairs, the mechanic typically gets system data from the OBD-II. By connecting to it with an OBD reader it can provide diagnostic trouble codes that help identify needed repairs and maintenance.

Does my car have OBD-II?

Whether you have this system depends on the model year of the car. The first generation OBD was developed in 1988 and the OBD-II was developed in 1992. Some cars manufactured between 1992 and 1995 were required to have an OBD-II. After 1996, the Environmental Protection Agency (EPA) required all cars and light vehicles (like pickups) to have OBD-II for monitoring emissions and certain engine components.

How to find an OBD-II port

The OBD-II port is commonly found on the driver's side dash just to the left under the steering wheel (locations 1 to 3, below). Other common locations include the driver's side kick panel, center console and glove compartment (locations 4 to 8, below).

Progressive has an online tool to help you find the location of the OBD-II port for your particular vehicle.

How OBD-II can help you save on auto insurance

Some car insurance companies offer "usage-based insurance" programs that use information on your driving habits to help determine discounts and your car insurance rate. For these programs, a telematics device connects to the OBD-II port and can record how many miles you drive, the time of day, speed, braking, when air bags are deployed and more. In newer cars with safety systems like forward collision warnings, the ODB-II will record related data.

Then with a mobile app you're able to monitor your trips with data collected from the ODB-II.

Here are some auto insurance companies that offer usage-based insurance discounts that use a telematics device with a car's OBD-II.

Insurance company Usage-based insurance program highlights
Allstate Drivewise
  • 5% cash back when you start the program.
  • Up to 13% cash back for every six months of safe driving.
  • Allstate rewards for completing safe driving challenges.
American Family Insurance KnowYourDrive
  • 5% discount when you start the program.
  • Up to 40% discount after an evaluation period.
Esurance DriveSense
  • Automatic discount when you sign up.
  • Additional discounts at the time of policy renewal.
Metromile Pulse
  • Rates based on how many miles you drive.
Nationwide Insurance SmartRide
  • A discount when you sign up.
  • Up to 40% discount after completing the SmartRide program (approximately four to six months).
Progressive Snapshot
  • Automatic discount when you sign up.
  • Another discount applied to your premium after you complete the program (approximately six months).
Safeco Insurance RightTrack
  • After being tracked for 90 days you'll receive a 5% to 30% discount.
Source: EverQuote research. Availability and discount levels can vary by state.

There are also safe-driving apps that don't use the ODB-II port, such as EverQuote's EverDrive app. These use systems in your mobile phone to track things like speed, cornering and braking.