Diagnosing modern vehicle problems involves communicating with the onboard computer systems. These systems can run detailed diagnostics and store the results for later use. Often, this will trigger the check engine light, or sometimes log an issue for future reference. To access these diagnostics, you'll need a special tool to read the OBD codes. That’s where having an OBD2 scanner comes in handy. Here's how to use an OBD2 scanner on your vehicle.
Different OBD Scanner Types
Back in the early days of onboard diagnostics, it wasn’t exactly easy to interface with the computer. In some cases, you had to insert a jumper wire across the access port, turn the ignition key in a special pattern, and then count the number of times the “check engine light” flashed. Not exactly easy. True OBD scanners were the realm of dealership service departments. However, things changed in the early 1990s when OBD2 became the national standard.
Most OBD scanners you will come across now are code readers. They are designed to access the diagnostic code information stored by the onboard computer and display it to the user. It is a one-way street for the most part except having the ability to erase any stored diagnostic codes.
Some OBD scanners are also diagnostic tools that can not only read stored diagnostics codes but also communicate back to the onboard computer systems. For example, this Bosch OBD2 scanner can manually control components to test them. For example, it can open and close a drive-by-wire throttle body while the technician observes to make sure it is moving correctly. This is extremely handy when diagnosing an issue to help isolate components for testing. Unfortunately, a bidirectional OBD2 scanner requires a deep understanding of how a certain vehicle’s computer operates. OBD scanners with two-way communication capability are often much more expensive than a simple code reader.
How to Use an OBD2 Scanner: 7-Step Tutorial
Using an OBD2 scanner is fairly straightforward. We recommend taking a few minutes to read over the instruction manual for your particular OBD2 scanner so you are familiar with the buttons and screen.
1. Locate the OBD port. Federal law requires that the OBD port be located within two feet of the steering wheel. It is possibly located out in the open or behind a plug/cap/door.
2. Plug the OBD2 scanner into the OBD port.
3. Turn on the vehicle. For key start ignition vehicles, turn the ignition switch to the “on” position; it is not necessary to start the car. This puts the vehicle in “accessory” mode. For push-button start vehicles, refer to your owner’s manual for how to put the vehicle in “accessory” mode.
4. Once the vehicle is in “accessory” mode, the OBD2 scanner should begin communicating with the vehicle.
5. Following the instructions included with your particular OBD2 scanner, begin a code scan. This should only take a few minutes.
6. The OBD2 scanner will indicate if there are any stored codes found. Write down any fault codes so you can look them up later.
7. Once the OBD2 scanner has scanned the onboard computer, you may turn off the vehicle and unplug the scanner.
