How Do You Use An OBD2 Bluetooth Scanner?

How Do You Use An OBD2 Bluetooth Scanner - Featured Image

If you want to diagnose a problem with your car, you don’t necessarily need to take it to the auto mechanic shop. With the help of Bluetooth technology, you can download an app – or use a specialized device – which can forward your car’s diagnostic information to your phone.

OBD stands for On-Board Diagnostics, and basically, it’s just a standard which car manufacturers use so that people can have a unified system for identifying car problems.

In this article, we’ll teach you how to use an OBD2 Bluetooth scanner – or an app which mimics one – so that you can figure out what’s wrong with your car before buying replacement parts.

5 Steps To Use An OBD2 Bluetooth Scanner

Step #1 – Open The App Or Power On The Scanner

First, you’ll need either a smartphone app which performs the functions of an OBD2 scanner, or you’ll need to purchase one of the scanners on the market which are BT compatible.

You may need to purchase batteries for the device. Either way, power it up or start the app. Having the instructions nearby is a good idea too.

Step #2 – Find The Dash Port And Plug In The BT Dongle

Some newer cars may have a Bluetooth system integrated with their OBD functions, but most cars won’t. Instead, you’ll need to find the port for the OBD system. The port usually lives somewhere under the dashboard. You may need to look around for it deeply underneath the dash, depending on the car.

Most OBD ports look like a USB port but are a bit larger and blockier.

If your car doesn’t naturally have Bluetooth OBD, you’ll need to plug in a Bluetooth dongle which provides BT the system. These dongles are easy to purchase, and they should be inexpensive. If you purchased a separate OBD2 unit, it should come with the dongle.

The dongle is powered by the car’s battery, so you won’t need to worry about supplying it with power unless the car is dead. In the same vein, don’t leave the dongle plugged into the car overnight – it shouldn’t be drawing any power when it isn’t in use, but it’s better not to risk it.

Step #3 – Turn The Car On

Turn on the car. This will power up the BT dongle, and provide an initial report about the engine’s status to your scanner.

The report will be couched in certain trouble codes. The trouble codes are consistent across car manufacturers for the most part. Write down the trouble codes which pop up initially and make a note of any other information which the scanner tells you.

On some scanners, you may need to go through a menu to get to the trouble codes. This menu may be called something like “DTC” because DTC stands for Diagnostic Trouble Code.

As a rule of thumb, if a car’s check engine light is on, you’ll find at least one trouble code when you first attach the scanner and turn on the car. This shouldn’t alarm you – you’re just confirming what the light said.

If your car doesn’t start, you can skip this step and proceed to the next step. You’ll probably need to take your car to a professional to fix it at that point, however.

Step #4 – Press Scan

Once you have recorded the first screen of information, it’s time to conduct a deeper scan. Press the scan button on the scanner and wait a moment or two while it gathers the data.

Once again, you may need to go through a menu or two to get to the error codes. Make sure not to touch anything in any of the menus which aren’t trouble codes unless you are trying to modify the way the parameters of your engine’s performance.

OBD2 scanners can change many of the variables which the electronic control system of cars use to calibrate their engines, which means that they can be dangerous to change if you don’t know what you’re doing.

Step #5 – Look Up The Scan Codes

The trouble codes follow a predictable nomenclature which you can try to interpret if you’re interested in a challenge.

The nomenclature works something like this:

  • Codes starting with B pertain to the body; P codes pertain to the powertrain, and C codes pertain to the chassis
  • The second digit of the code indicates whether the code itself is specific to a certain manufacturer’s coding scheme, or whether it is a common enough issue that it will not vary between manufacturers; a 1 indicates that the code is manufacturer-specific, whereas a 0 indicates that the code is generic
  • The third digit is the specific system that is malfunctioning

Which Specific System Is Malfunctioning?

  • 1 or 2 identify the air and fuel system
  • 3 identifies the ignition system and spark plug
  • 4 identifies the catalytic converter and engine emissions monitoring systems
  • 5 identifies the idle engine governor and speed control system
  • 6 identifies the electronic control system of the vehicle and potentially the OBD itself
  • 7 and 8 identify the powertrain and transmission
  • 9 identifies the driver-adjusted control signals
  • The fifth digit is the specific error code for the system identified

Depending on the scanner or app you use, you may get higher level codes like Trouble Code 7 which doesn’t seem to give you enough information. For these, you’ll need to consult your manual or a licensed dealer.

You can also look up the trouble code on the internet to save yourself the time spent decoding. Remember to specify the make and model of your car to ensure that you get the most accurate answer possible.

With the help of the OBD2 scanner, you’ll be a lot closer to diagnosing and also solving your car problems. Things are not always as they appear, however. The scanner only tells you what the sensors in the car communicate.

If a sensor itself is failing but hasn’t totally failed yet, it can often provide your scanner with misleading information. Realistically, you’ll need to troubleshoot ever part along the way from the scanner to the part that seems to be malfunctioning if you want to be confident in the scanner’s diagnosis.

Brett Gordon

The engine behind editing at DigMyRide and the brains behind its build. During the day, Brett is a thirty-something dude from SoCal climbing the corporate ladder, but by night, he spends his time contributing to the online world of automotive tech & trends.