How to use an OBD Reader

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If you're like most people, the last thing you want to include in your busy schedule is servicing your car. There you are, driving in traffic on your way to work, you're late, you're upset, and that's when the "Check Engine Light" comes on. That little amber engine-shaped light is glaring at you, and you don't know if it is saying you have a loose gas cap, it's time to change your oil, your oxygen sensor is malfunctioning, your engine is overheating, or your catalytic converter is about to blow. Luckily, there's an easy way to find out what's going on thanks to a modern miracle called an OBDII Reader/Scanner.
 
Perhaps you are a do-it-yourself mechanic who enjoys handling repairs on your vehicle or maybe you would just like to be able to read your car's error codes so you can better understand and communicate with the technician who is working on your repairs. In either case, you've come to the right place if you'd like to know about on-board diagnostic tools. First some history on OBD.

What's an OBD Reader?

On-Board Diagnostics (OBD) is an electronic automotive monitoring system that offers vehicle diagnosis of various error codes via computer systems and sensors throughout your car. It gives auto technicians access to subsystem information to monitor your vehicle's performance in order to carry out repairs and adjustments as needed. Basically, OBD retrieves vehicle diagnostic information that is generated by your car's various computer systems. An OBD Reader is a device that allows you to track when various parts are wearing out, diagnose vehicle problems before they occur, and fix them before they become a problem.
OBD came into use in the 1980s as part of a vehicle's onboard computer to show malfunction indicator lights. It could tell you that a problem was detected but not necessarily the nature of the problem or how to fix it. The second generation of this system is known as OBDII and provides real-time data as well as a standardized series of error codes which are used to diagnose and repair malfunctions. Before OBD was standardized, automakers would each create their own specific system and codes for reporting problems. In 1988, the Society of Automobile Engineers (SAE) suggested a standardized diagnostic connector and set of universal test signals. The state of California mandated that all vehicles have some kind of on-board diagnostics in 1994 and by 1996 OBDII became mandatory for all cars manufactured in the United States. The European equivalent became mandatory in 2001.
 
OBDII is the current standard diagnostic tool and has become more sophisticated and elaborate in recent years to provide Diagnostic Trouble Codes (DTCs) for problems with the engine and transmission, emission control systems, ignition, and more. On-Board Diagnostics used to be something that only auto mechanics could access, but today you can purchase an OBDII Reader that scans your car's error codes and lets you know where problems exist so they can be fixed before they become a problem, for under $100.

How to use an OBD Reader

There is an OBDII port in your car that allows you to plug in an OBD Reader. It is usually located underneath the steering column on the driver's side and is covered by an access door. A 16-pin connector is plugged into a cable that leads to your OBD Reader. You can find the location of your OBD Port in your car's Owner's Manual. OBDII Scanner/Code Readers are available at auto parts stores and on Amazon for as little as $25 that meet most consumers' needs. For around $100 you can even get a Bluetooth scan tool that connects to your smartphone wirelessly via an online app to decipher your vehicle's error codes. These diagnostic tools even generate repair reports containing specific causes and reported fixes for any vehicle make and model. Many of these Bluetooth OBDII Readers will store and log codes on your smartphone or laptop.
Connecting your OBD Reader
First, read the manual on your OBD scan tool and any documentation that comes with it. Locate your car's diagnostic link connector (also known as the OBD Port) by looking it up in your Owner's Manual and plug the standard OBDII connector cable into your car's port. Turn on the power to your car to power up the Code Reader. It may ask for your car's Vehicle Identification Number (VIN) to get started. If so, you'll find your VIN number on the driver's side dash next to the windshield, on a sticker under the hood, or on your title, registration, or auto insurance card.

Once the reader recognizes your vehicle, press the "scan" button on the reader/scanner and follow the directions on the device screen. A scan usually only takes a few seconds. Follow the screen prompts to find out if your vehicle has any error codes. If it does, write down the code numbers. You can use the information to diagnose repairs, order parts, and clear the error codes once the job is done. 

The information can also be used to find out if the code was a one-time issue, or an on-going problem and you can use the information to better communicate what is going on with the vehicle to your service writer or technician at your dealership's service center.

After you have the error codes, you can search the Internet to deduce specific problems and diagnose repair options. Today's more sophisticated OBD Readers will give you the error code and its corresponding description right on the screen. Some even go so far as to suggest which parts might need to be replaced. At the very least, you can use the information from the scan to validate your mechanic's assessment based on his or her own diagnostic scan at the shop.

Things to know before you Buy an OBDII Reader

It's important to do a bit of research before you purchase an OBDII Reader. An online search will reveal that there are literally hundreds of OBDII Readers on the market with costs that range from $25 to over $800 for general consumer units. Which one you chose will depend on how much information you want to know and how sophisticated and extensive the vehicle information is.
 
It is best to contact the automaker or a local dealership for your make and model of car to find out which specific OBDII system your car is using. More expensive tools can be used on more than one brand of vehicle. Just be sure your OBDII Reader will work on your specific car (or cars) before you hit the "Buy" button.
 
Keep in mind that it is best to seek advice from an ASE-certified auto technician when diagnosing error codes. It's easy to buy the wrong part for a DIY repair. Also, if your vehicle is still under the manufacturer's warranty, repairing or replacing certain emission systems and catalytic converters yourself could possibly void your warranty.

Understanding OBDII Codes

Once your OBDII Reader has displayed error codes, you'll need to read and understand what they mean about your vehicle's condition. All error codes begin with a letter of the alphabet followed by four numbers. The various letters relate to the following systems:
 
  • P is for Powertrain and pertains to problems with your car's engine, transmission, emissions, fuel, or ignition.
  • B is for Body and means the error relates to such things as the power steering, seatbelts, or airbags.
  • C is for Chassis and relates to problems with the brakes, brake fluid or anti-lock braking system, or issues with the axles.
  • U is for Undefined and corresponds to any systems not covered above.
As for the error code's numbering system, the first number lets you know if the error code is a generic problem (0) or if it is specific to the automaker (1). The second number indicates a specific part of the vehicle, and the last two numbers reveal the exact problem your car is experiencing. You'll find a complete list of OBDII error codes here. Once the OBDII Reader has displayed the error codes and you have written them down or transferred them to your smartphone or laptop, turn off the car and unplug the cable or wireless device.
 
Let Lithia Help
Today's cars are more high tech and sophisticated than ever and while an OBDII Reader can tell you what system has a problem, it can't tell you how to fix the problem. That's where the factory-trained technicians and service experts at Lithia Motors come in. Bring your vehicle to the Lithia Motors service center near you to avoid expensive DIY mistakes. We'll diagnose any problems your car may have, use the manufacturer's suggested OEM parts to repair your vehicle, and get you back on the road quick and easy.