How To Use An OBD2 Scanner – A Step-by-step Guide

Cars have evolved over the years. Auto manufacturers keep improving car safety, performance, handling, drivability, and stability on the road. They achieve this by adding several car sensors and components. Think of the Parking assist, forward collision warning, LCD monitors, parking sensors, driver attention monitor, blind spot monitor, lane-keeping assist, night vision – the list continues.

These sensors and components are built with new technologies and innovation. By equipping these sensors, auto manufacturers improve safety and overall performance.

Other sensors, functions, and technologies monitor the internal engine and transmission health. Some will display similar symptoms when they fail, making it challenging to track the root cause. Therefore, you need to learn how to use an OBD2 scanner to track issues and pull logged error codes.

This will make it easier to track the problem and fix it as soon as possible. Here, we’ll discuss how to connect OBD2 scanner, what the OBD2 stands for, and, more importantly, how to read OBD2 scanner.

how to use obd2 scanner bluetooth

What does OBD stand for?

OBD stands for onboard diagnostics. It is an onboard self-diagnostic mechanism prerequisite for small cars and lightweight and medium-weight trucks. This mechanism has hardware where you can plug in a scan tool and software that communicates with the car computer.

When the car computer detects a fault and throws an error code to pop up on the dashboard screen, a service technician will have to plug in a scanner to pull out the registered codes. So what can you do with an OBD2 scanner? The OBD technology helps technicians and DIYers track and rectify issues easily.

How To Use An OBD2 Scanner Step-By-Step

How to use a diagnostics code reader is a skill set every mechanic and DIYer should have. The process is quite easy to learn. Keep reading as we’ll explain it in a simplified guide.

Step 1: Locate the OBD2 port

Every vehicle built from 1996 upward in the US has an onboard diagnostic (OBD) port or diagnostic link connector (DLC). The OBD2 port is located beneath the steering wheel on the driver’s side. It has a 16-pin connector usually covered with a flap or door.

Step 2: Plug in the diagnostic machine

Once you locate the OBD2 port, switch off the vehicle and connect the diagnostic machine to the vehicle DLC port. OBD2 scanning machines come in various designs. Some have a removable cable, some have non-detachable cables, and others have a DLC connector and a Bluetooth connection.

With a Bluetooth OBD scanning machine, you can connect and diagnose your car with a smartphone or laptop. The diagnosing process remains the same. The only difference is connecting the car to your phone. Kindly note that you must install the scanning app on your device before diagnosing the car.

So if you want to know how to use obd2 scanner Bluetooth, the process is still the same. After a successful connection, see the instructions on the scanning tool and your service manual if you should keep the car ON position or on idle. This is very crucial for an accurate reading.

Step 3: Input the data requested

The scan tool comes in various sizes and designs, with several functionality levels. Some machines will come up once you connect them to the vehicle, and others will require you to boot them. However, some scan tools will request you to input the car VIN before it can recognize the vehicle.

The diagnostic scan tool may ask for your engine make and model. Go ahead and input the required information. The VIN is usually inscribed on a sticker on the bottom of your windscreen on the driver’s side. Check the front end of the car frame or under the hood close to the latch if it’s not on the windscreen.

Step 4: Read the logged fault codes

Once connected, the scanning will display all error codes in the car’s memory. Some scan tools will display MENU, requesting you to select the module or system you want to diagnose. Follow the instructions and retrieve the logged error codes.

Step 5: Understand and Interpret the fault codes

The diagnostic machine will display the fault codes, but it won’t solve the problem. Here’s where things get tricky. With the fault codes retrieved, it’s time to interpret them.

Diagnostic trouble codes have five alphanumeric numbers. It typically starts with a letter and is followed by four numbers. Here’s the meaning of the letters.

B (body): This shows the registered issue is body-related. For instance, fault codes with the letter B are related to seatbelts, airbags, and power steering. 

C (chassis): This shows the issues are related to the chassis. For example, anti-lock braking systems, axle issues, and brake fluids.

P (powertrain): The P fault codes indicate issues with the fuel systems, emission, ignition, transmission, and engine.

U (undefined): The U means undefined issues that do not belong to the B, C, or P category.

Now that you know what the letters mean. So, let’s examine the numbers.

  • The first number after the letter indicates whether the fault code is generic (0) or specific to the vehicle manufacturer (1).
  • The next number point to the faulty car component.
  • The third and fourth numbers show the specific car problem.

After retrieving the logged error codes, write them down and turn off the vehicle. So, if you’re asking, do I need an OBD2 scanner? Of course, you already know the answer. Every DIYer and mechanic should have a scanning machine.

Step 6: Is it what you can do?

The scan tool is so crucial that it tells you the probable causes of the problems in a car in a few minutes. But it can’t fix the problem. Therefore, find out how serious the error is and see if it’s what you can do.

Some error codes are minor that a beginner can fix, while others are severe and require intermediate or advanced service technicians. Regardless of the severity, contact a certified auto mechanic if you don’t trust your guts or are not familiar with the underhood working principles.

Step 7: Erase the fault codes

After repairing or replacing faulty components, test the vehicle for around 30 to 45 minutes. The logged code should have disappeared by now. However, if the code is still there, connect your scan tool and erase it.

Sometimes, professional mechanics erase registered codes without repairing or replacing any components. This is because the car computer can trigger an error code when there is no existing issue. In such a scenario, if the code reappears after erasing it, it means there is a problem that needs attention.

Different Types of OBD2 Diagnostic Tools and Their Uses

There are three types of OBD2 diagnostics tools. They include basic, DIY, and professional scan tools. As the name indicates, they can provide varying information.

how to read obd2 scanner

Basic diagnostic tools

As the name suggests, this diagnostic scan tool has basic features. It is quite affordable and simple to use. These scan tools look like DIY tools with a small screen. It’ll only display the fault codes and let you get the possible causes online or on an OBD2 code booklet.

This is the right tool for those unfamiliar with the underhood working principles but want to pull the registered codes and take the car to their mechanic afterward. However, it can be a better option for experienced low-budget mechanics.

DIY diagnostic tools

DIY diagnostic scan tools are more advanced than basic scanning tools. They are meant for both mechanics and DIYer car owners. This scanning tool will display the registered fault codes, the meaning, and probable causes. In addition, some DIY tools will offer live data and potential fixes to resolve the problem.

They come in various designs. Some look like basic tools but with more features. Other has Bluetooth connection. This means you can plug in the tool and connect it to your phone or laptop.

Professional diagnostic tools

These are professional-grade scanning machines. They fall in the best categories. They are specifically designed for gearheads. You’ll see these machines in certified auto repair shops.

The professional diagnostics tools provide in-depth data and suggest possible repair solutions. They can pull and save data and allow you to compare them as you progress with the repair. This is very expensive and not recommended for a DIYer. Unless you have a repair shop where you diagnose cars regularly, you may be spending money unnecessarily.

You can get any of these diagnostics scan tools online and in a local auto shop. You can get the tool in online shops like eBay, AutoZone, and Amazon. If you get the tools from these online stores, you may want to know how to use them. How to use a code reader from AutoZone, eBay, or amazon is the same as the above guides.


Q: Does a car have to be running to use an OBD2 scanner?

Generally, you should turn the ignition to the ON position or start the vehicle before scanning it. Failure to do this may render the scanning tool inoperable until you follow the instructions. Studying the instructions on the scanning machine for optimal guides is crucial. This will help you avoid misdiagnosis.

Q: Can you damage your car using an OBD2 scanner?

The straightforward answer is no. You can’t damage your car with an OBD2 scan tool. In fact, it is completely safe to drive with the OBD2 scanner plugged in. It is even safer to diagnose the vehicle with the engine running to avoid damaging the scanning machine software.

In any case, diagnosing your vehicle with a scan tool with a frayed, burnt, or open wire can affect the car powertrain control module (PCM). Therefore, always ensure the scan tool is properly managed.

Q: Does OBD2 drain the battery?

Most OBD2 scan tools are powered once connected to the car, even when the car is not running. The amount of power it draws depends on the specific diagnostics machine. For example, a Bluetooth scan tool will always pull power from the car to send signals to the app on your phone or laptop.

A poorly designed diagnostic machine can drain your battery life when left plugged into the vehicle diagnostic link connector.

Q: Do all OBD2 scanners erase codes?

I don’t know, but most basic OBD2 scanners (the ones with the least features) can pull and clear fault codes. But I haven’t seen any scan tool without this feature. In any case, checking the features before purchasing a scan tool is advisable.

Q: Is my car OBD1 or OBD2?

Cars built in 1996 and afterward are OBD2. This is specifically for cars built or marketed in the United States. Categorically speaking, if your car is OBD1 or OBD2, locate the Vehicle Emission Control Information card. This is usually located under the hood. It tells you if the vehicle is OBD2 certified.

Q: What data can you get from OBD2?

The OBD2 scan tool allows the mechanic, dealerships, or car owners to view various data. These include

  • Logged fault codes
  • How many miles driven with MIL on
  • Vehicle identification number (VIN)
  • Number of ignition cycles
  • Emission readiness status
  • Status of engine warning lights
  • O2 sensor test results
  • Freeze frame: a data detailing when the fault code issue happened
  • Real-time parameters: coolant temperature, airflow rate, speed, RPM, spark advance, pedal position, etcetera.

Final Words

In summary, you’ll no longer ask, what can you do with an OBD2 scanner? The onboard diagnostic scanning tool is a must-have for all DIYers and car mechanics. They come in various sizes, designs, shapes, and prices, making them accessible to everyone.

You can get one for $30 or even lower if you’re on a low budget. However, the lower the price, the fewer features it comes with. There are also DIYer and professional scan tools available. The choice is yours. Get one and start diagnosing your vehicle using the how-to-use OBD2 scanner guide above.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

Leave a Reply

Your email address will not be published. Required fields are marked *

Recent Posts