What Is the OBD-II Port and What Is It Used For?
If you purchased a car after 1996, chances are it has an OBD-II (On-board diagnostics II) port. Every car or truck on the road manufactured after 1996 is legally mandated to have one installed.
OBD-II is an on-board computer that monitors emissions, mileage, speed, and other data about your car. It’s connected to the Check Engine light, which illuminates when the computer detects a problem.
The OBD-II on-board computer features a 16-pin port located under the driver’s side dash. It allows a mechanic or anyone else to read the error code using a special scan tool.
OBD-I vs. OBD-II
Before OBD-I, each manufacturer had their own set of standards for OBD, meaning that mechanics had to buy expensive scan tools for each manufacturer. OBD-I was first introduced in 1987, and started the standardization of onboard diagnostics.
It had sensors that detected emissions and was able to minimize them through emissions-controlling valves. However, it had many problems and shortfalls.
As a result, in 1996 car manufacturers started to equip cars and trucks with an OBD-II port. Every system is mostly the same, but there are slight variations. These are known as protocols, and are specific to vehicle manufacturers.
There are five basic signal protocols:
- SAE J1850 PWM: Pulse Width Modulation, used in Ford vehicles
- SAE J1850 VPW: Variable Pulse Width used in General Motors vehicles
- ISO9141-2: Used in all Chrysler and a variety of European or Asian vehicles
- ISO14230-4 (KWP2000): Keyword Protocol, used in a variety of European and Asian imports as well as Honda, Jeep, Land Rover, Subaru, Mazda, Nissan, and more
- ISO 15765 CAN: Controller Area Network, used on all vehicles manufactured after 2008
Pins 4 and 5 in all protocols are used for ground connections, and pin 16 is used for power from the car’s battery.
Once the computer senses a problem with the engine or any other component of the car it’s monitoring, it’ll trigger the Check Engine light. Some vehicles also blink the engine light if the problem is a very serious one.
How Does OBD-II Work?
Diagnostic Trouble Codes (DTC) are stored in the computer system. Codes can vary from one manufacturer to another. However, anyone with an OBD-II scan tool can connect to the port and read the diagnostic trouble codes from the computer.
The reason any OBD-II scan tool can read the codes is because of the standardized pinout. Scan tools can read from any of the protocols listed above. The standardized pinout is as follows.
- Pin 1: Used by manufacturer
- Pin 2: Used by SAE J1850 PWM and VPW
- Pin 3: Used by manufacturer
- Pin 4: Ground
- Pin 5: Ground
- Pin 6: Used by ISO 15765-4 CAN
- Pin 7: The K-Line of ISO 9141-2 and ISO 14230-4
- Pin 10: Used only by SAE J1850 PWM
- Pin 14: Used by ISO 15765-4 CAN
- Pin 15: The K-Line of ISO 9141-2 and ISO 14230-4
- Pin 16: Power from the car battery
OBD-II scanners can connect to these ports and identify the trouble code from any manufacturer that uses one of the OBD-II protocols.
What Can Be Hooked Up to the OBD-II Port?
Traditionally, a mechanic would hook up a scan tool to the port to read the DTC. Less expensive scanners would only provide a numeric code, which the mechanic would then look up from the manufacturer’s manual or service website. More expensive scanners provide will provide text error codes.
However, in recent years, there are more advanced tools available for regular drivers who don’t want to have to depend on a mechanic to find out what’s wrong with their car.
One example is the OBDLink SX USB Adapter by ScanTool that lets you read the trouble codes with your laptop.
This device lets you plug directly into the OBD-II port, and plug the other end into the USB port of your Windows laptop.
This transforms your computer into an advanced OBD scanner tool, plus you can even clear the Check Engine light with the OBDwiz diagnostics software.
If you prefer a wireless solution, ScanTool also offers OBDLink MX Bluetooth.
This device lets you read your car diagnostics with your Windows blue-tooth enabled laptop, or your Android device.
It comes with free Windows and Android software to diagnose your car remotely.
Other Mobile OBD-II Scanner Apps
The computer system in your car is constantly monitoring various systems and components throughout your car.
This means that any device that plugs into the port can read the same information and pass it along to your mobile device. Imagine opening an app on your phone and viewing your vehicle’s current fuel consumption, temperatures, oil pressures, and more.
It’s possible today with any of the devices and apps listed below.
This wireless OBD reader by BAFX Products transforms your iOS device into an impressive, advanced OBD tool. Not only can you read all diagnostics data from your car, but you can also monitor real-time data like:
- Engine temperature
- Fuel rate
- O2 sensor voltages
- Battery voltage level
- Time your engine has been running
It’s a useful tool to monitor data about your car systems that your own dashboard doesn’t show you.
Keep in mind however that the third party apps that work with this device aren’t free.
If you’re looking for an inexpensive solution, you can’t go wrong with this OBD-II diagnostic scanner for Android by Panlong.
This device works with a variety of Android apps like Torque Pro, Torque Lite, or OBD Car Doctor. Just enable Bluetooth and you can view various sensor data, and diagnose error codes when your Check Engine light turns on.
Unlike most other devices in this price range, this device also lets you clear the error codes for minor things like a loose fuel cap.
Another inexpensive solution for your Android device is the iSaddle Super Mini Bluetooth OBD2 Scan Tool.
Just enable Bluetooth on your phone and connect to this scan tool to read information from your OBD-II port. The device can read all OBD-II protocols. You can use it with Torque Android software, or even ScanMaster software for your Bluetooth-enabled laptop.
And if it matters to you, you have a choice of three port adapter colors to choose from!
The BlueDriver Bluetooth Professional OBDII Scan Tool is for anyone who would like a more functional OBD-II port scanner. This scan tool is Bluetooth-enabled, and works with both Android and iOS devices.
It’s somewhat more expensive than other wireless port-readers on the market. However, it comes the sort of features you’d expect from the same expensive scan tools that mechanics use.
The device lets you use your mobile app to read and clear both basic and advanced error codes. It also includes advance tests like misfire counts, live data as digital readouts and graphs, and even repair reports from a frequently updated online database.
Reading and clearing error codes is useful, but if you really want to have access to real-time data, then the Automatic PRO AUT-350 OBDII adapter is the way to go.
It’s one of the more expensive options, but the features are simply amazing.
- 3G connectivity provides remote vehicle information no matter where you are.
- Get real-time vehicle data even when you’re far from your vehicle.
- Detects crashes and sends emergency services to help you.
- Integrates with the Echo, Nest, and IFTTT.
- GPS tracking enabled so you always know the location of your car.
While the price sets this advanced scan tool within the range of many expensive tools mechanics use , all of these impressive features make it well worth the cost.
Taking Advantage of Your OBD-II Port
The OBD-II port has been available in vehicles for many years, but only recently has been accessible to regular drivers. Having these devices and apps gives you much better insight into what’s going on with your vehicle, long before any major problems ever occur.
Many of these port scanners come with location tracking features. If that’s what you’re more interested in, then make sure to check out some of the best GPS trackers for your car . Even though they don’t show you your car diagnostics, at least they’ll make sure you never get lost.