How to Use a CAN OBD2 Car Scanner Tool: Your Step-by-Step Guide

For any car owner, understanding the health of your vehicle is crucial. When that pesky check engine light illuminates on your dashboard, your first thought might be a costly trip to the mechanic. However, with a Can Obd2 Car Scanner Tool, you can take the first step in diagnosing and potentially resolving car issues yourself, saving time and money. This guide will walk you through how to effectively use an OBD2 scanner, empowering you to understand your vehicle’s diagnostics.

Locating the OBD2 Port in Your Vehicle

The OBD2 port is the universal access point for retrieving diagnostic information from your car’s computer system. In almost every passenger vehicle manufactured since 1996, you’ll find a standardized 16-pin Diagnostic Link Connector (DLC). This port is typically located inside the cabin.

The most common location is underneath the dashboard on the driver’s side. Look below the steering wheel column and above the pedals. You might need to crouch down to get a good view. It’s usually not hidden behind a panel, but it can sometimes be tucked away.

While the driver’s side dashboard is the primary location, there are a few other places where you might find the OBD2 port:

Center Console: In some vehicles, especially larger SUVs or trucks, the port might be located in the center console, either in the front or rear.
Passenger Side Dashboard: Less common, but occasionally the OBD2 port can be found under the passenger side dashboard.
Behind an Ashtray or Panel: In older models or specific makes, the port may be concealed behind a small, removable panel or ashtray. Check your vehicle’s owner’s manual for the precise location if you are having trouble finding it.

The OBD2 port is female and trapezoid-shaped, with 16 pins. It’s designed to be easily accessible and recognizable.

Connecting Your CAN OBD2 Scanner Tool

Connecting your OBD2 scanner is a straightforward process, designed for ease of use even for those with limited car repair experience. Here’s a step-by-step guide to ensure a proper connection:

Turn Off the Ignition: Before you begin, make sure your vehicle’s ignition is completely turned off. This is a safety precaution and ensures proper communication between the scanner and your car’s computer.
Locate the OBD2 Port: Use the guidance in the previous section to find the OBD2 port in your vehicle.
Align the Scanner Connector: Take your OBD2 scanner tool and examine the male connector on its cable. It will also be trapezoid-shaped to match the port in your car. Align the shape of the scanner’s connector with the OBD2 port. It only fits in one orientation, so do not force it.
Connect the Scanner: Gently but firmly push the scanner’s connector into the OBD2 port. You might feel a slight resistance as the connectors engage. A little wiggle can help ensure a secure connection. You should feel or hear a click as it fully seats.
Turn the Ignition to the “ON” Position (Engine Off): Once the scanner is connected, turn your car’s ignition to the “ON” position. This means turning the key to the point where the dashboard lights illuminate, but do not start the engine. This provides power to the OBD2 port and your scanner.
Power Up the Scanner: In most cases, the OBD2 port will automatically power up your scanner tool. You should see the scanner’s screen light up or indicators showing it’s receiving power. If your scanner has a separate power switch, turn it on now.
Wait for Boot Sequence: Give your scanner a moment to complete its boot sequence. This is usually a brief process. The scanner will then typically display a welcome screen or main menu.
Follow On-Screen Prompts: Your OBD2 scanner tool may guide you through initial setup steps. This might include selecting your vehicle’s make and model, or entering the VIN (Vehicle Identification Number). Follow the on-screen instructions provided by your scanner.

Navigating the OBD2 Scanner Menu and Understanding Functions

Once your CAN OBD2 car scanner tool is connected and powered up, you’ll be greeted by a menu on its display screen. The exact menu options and interface will vary depending on the type and features of your scanner, ranging from basic code readers to more advanced professional-grade tools. However, most OBD2 scanners offer a set of core functions that are essential for diagnosing car problems. Here’s a breakdown of common menu options:

Read Codes (or Diagnostic Codes): This is the primary function for diagnosing issues. Selecting “Read Codes” instructs the scanner to communicate with your car’s computer and retrieve any stored Diagnostic Trouble Codes (DTCs). These codes are alphanumeric codes that correspond to specific problems detected by the vehicle’s onboard diagnostic system. The scanner will display the DTC number (e.g., P0301) and often a brief description of the fault. If multiple codes are present, the scanner will usually scroll through them.
Erase Codes (or Clear Codes): After you have diagnosed and repaired the issue indicated by a DTC, you can use the “Erase Codes” function to clear the codes from your car’s computer memory. This will also turn off the check engine light if it was illuminated due to the fault. Typically, the scanner will ask for confirmation before clearing codes to prevent accidental erasure. Important Note: Only erase codes after you have properly addressed the underlying problem. Erasing codes without fixing the issue will only temporarily turn off the warning light, and the problem and code will likely return.
Live Data (or Data Stream): This powerful feature allows you to monitor real-time sensor readings from various systems in your vehicle while the engine is running. You can view parameters like engine temperature, RPM, oxygen sensor readings, fuel trim, and many more. Live data is invaluable for diagnosing intermittent problems or monitoring sensor performance to pinpoint the source of an issue. For example, you can observe if an oxygen sensor is switching values correctly or if a temperature sensor is reading within the expected range.
Freeze Frame: When a DTC is set, the vehicle’s computer often captures a “snapshot” of sensor data at the moment the fault occurred. This freeze frame data can provide valuable context for understanding the conditions under which the problem happened. It can include parameters like engine speed, engine load, fuel pressure, and more, helping you analyze the problem more effectively.
Vehicle Info (or Vehicle Information): This option typically displays basic information about your vehicle as stored in its computer system. This can include the VIN, calibration IDs, and other identifying data.
I/M Readiness (or Inspection/Maintenance Readiness): This function is particularly useful for emissions testing or smog checks. I/M Readiness monitors the status of various emissions-related systems in your vehicle, such as the oxygen sensors, catalytic converter, evaporative system, and EGR system. It indicates whether these systems have completed their self-tests and are ready for an emissions test. If any of these readiness monitors are incomplete or showing faults, your vehicle may fail an emissions inspection.

Most scanners use arrow buttons for navigation and an “Enter” or “OK” button for selections. A “Back” or “Escape” button allows you to return to the previous menu. Refer to your scanner’s user manual for specific instructions on navigating its menu and using its features.

Decoding Diagnostic Trouble Codes (DTCs)

When you use the “Read Codes” function, your CAN OBD2 car scanner tool will display DTCs. These codes follow a standardized format, making them universally understandable across different vehicle makes and models. A DTC is always a five-character code consisting of one letter followed by four numbers, like P0301.

Let’s break down the meaning of each position in the DTC:

First Character – Letter: This letter indicates the primary vehicle system where the fault is located:
- P (Powertrain): Relates to engine, transmission, fuel system, and emissions control systems. This is the most common category for check engine light issues.
- B (Body): Indicates problems with body-related systems, such as airbags, power windows, interior lighting, and other comfort and convenience features.
- C (Chassis): Refers to chassis systems, including ABS (Anti-lock Braking System), traction control, suspension, and steering.
- U (Network or Undefined): Signals communication or network-related issues between different electronic control modules in the vehicle.
Second Character – Digit (0 or 1): This digit specifies whether the code is generic or manufacturer-specific:
- 0: Indicates a generic or standardized OBD2 code. These codes are the same across all vehicle manufacturers.
- 1: Indicates a manufacturer-specific or enhanced code. These codes are defined by the specific car manufacturer and may provide more detailed information about the fault than generic codes.
Third Character – Digit: This digit further identifies the specific subsystem within the main system (indicated by the first letter):
- 1: Fuel and Air Metering
- 2: Fuel and Air Metering (Injector Circuit)
- 3: Ignition System or Misfire
- 4: Auxiliary Emission Controls
- 5: Vehicle Speed Control & Idle Control System
- 6: Computer Output Circuit
- 7, 8, 9: Transmission
- A, B, C: Hybrid Propulsion Systems
Fourth and Fifth Characters – Digits: These final two digits provide even more specific information about the fault within the identified system and subsystem. There are hundreds of possible combinations, each with a specific meaning.

Example: Decoding P0301

Using the breakdown above, let’s decode the example code P0301:

P: Powertrain (engine, transmission, emissions)
0: Generic code (standardized across manufacturers)
3: Ignition System or Misfire
01: Specific fault within the misfire category – in this case, Cylinder 1 Misfire.

Therefore, P0301 indicates a generic powertrain code related to a misfire detected in cylinder number 1.

While some scanners provide a brief description of the code, for a more detailed understanding of DTCs, you can:

Consult your vehicle’s repair manual: This is the most comprehensive resource for manufacturer-specific code definitions and troubleshooting procedures.
Use online DTC lookup websites or apps: Many websites and mobile apps allow you to enter a DTC and get a detailed description, potential causes, and possible solutions. Reputable sources are key for accurate information.
Refer to automotive repair databases: Services like ALLDATA or Mitchell OnDemand (often used by professional mechanics) provide extensive diagnostic information.

Understanding DTCs is the key to effectively using your OBD2 scanner tool for car diagnostics and repair.

Saving Money with a CAN OBD2 Car Scanner Tool

Investing in a CAN OBD2 car scanner tool can lead to significant savings on car repairs and maintenance over time. Here are several ways an OBD2 scanner can help you save money:

Early Problem Detection and Diagnosis: When your check engine light comes on, it can be tempting to ignore it or fear the worst. An OBD2 scanner allows you to immediately read the trouble codes and get an initial understanding of the problem. This early detection can prevent minor issues from escalating into major, more expensive repairs.
Avoid Unnecessary Mechanic Visits for Simple Issues: Sometimes, a check engine light can be triggered by a minor issue, such as a loose gas cap or a faulty sensor that is easily replaceable. By using a scanner, you might be able to identify and resolve these simple problems yourself, avoiding diagnostic fees at a mechanic shop.
Informed Mechanic Visits: Even if you need to take your car to a mechanic, knowing the DTCs beforehand empowers you to have a more informed conversation. You can communicate the specific codes to the mechanic, potentially speeding up the diagnostic process and ensuring you are both on the same page regarding the problem. This can also help prevent unnecessary repairs being suggested.
DIY Repairs and Maintenance: For those who are comfortable with basic car maintenance, an OBD2 scanner can be an invaluable tool for DIY repairs. By identifying the faulty component (e.g., an oxygen sensor, mass airflow sensor), you can often replace it yourself, saving on labor costs at a repair shop. The scanner can also be used to clear the codes after the repair is completed.
Smog Check Readiness: As mentioned earlier, the I/M Readiness function can help you ensure your vehicle is likely to pass an emissions test. By checking readiness monitors before going for a smog check, you can identify and address any emissions-related issues beforehand, avoiding costly re-tests and potential fines.
Monitoring Vehicle Health and Performance: Features like Live Data allow you to monitor your vehicle’s performance in real-time. This can help you detect subtle issues or performance degradation before they become major problems. Regularly checking live data can aid in preventative maintenance and ensure your car is running efficiently, potentially improving fuel economy and extending the lifespan of components.

By empowering you to understand your vehicle’s diagnostic information, a CAN OBD2 car scanner tool is a valuable investment for any car owner looking to save money and take a more proactive approach to car maintenance.

Choosing the Right CAN OBD2 Scanner Tool

The market offers a wide variety of CAN OBD2 car scanner tools, ranging in price and features. When choosing a scanner, consider your needs and budget.

Basic Code Readers: These are entry-level scanners that primarily focus on reading and clearing DTCs. They are affordable and suitable for basic check engine light diagnosis.
Mid-Range Scanners: These scanners offer more features, such as live data streaming, freeze frame data, and I/M readiness testing. They provide a more comprehensive diagnostic capability for DIYers and enthusiasts.
Professional-Grade Scanners: These are advanced tools used by mechanics and automotive technicians. They offer extensive features, including advanced diagnostics, bidirectional controls, system tests, and manufacturer-specific functions. They are typically more expensive but offer the most comprehensive capabilities.

Consider these factors when selecting a scanner:

Features: Determine which features are important to you based on your diagnostic needs. Do you need live data, freeze frame, or just basic code reading?
Compatibility: Ensure the scanner is compatible with your vehicle’s make and model. Most OBD2 scanners are universally compatible with post-1996 vehicles, but it’s always best to double-check.
Ease of Use: Look for a scanner with an intuitive interface and easy-to-navigate menus.
Update Capability: Some scanners allow for software updates, which can add new features, improve compatibility, and expand code definitions.
Price: Set a budget and compare scanners within your price range, balancing features and cost.

Investing in the right CAN OBD2 car scanner tool can be a smart decision for any car owner, providing valuable diagnostic capabilities and potential cost savings for years to come.

FAQ/People Also Ask

How do you use OBD II scanner?
Plug the scan tool connector into the OBD2 port under your dashboard, turn the ignition to the ON position (engine off), and follow the on-screen instructions to read codes, view live data, or perform other diagnostic functions.

Does car have to be running to use OBD2 scanner?
No, in most instances, you can read trouble codes and access most functions with the ignition in the ON position (engine off). Live data monitoring typically requires the engine to be running.

How do I read my OBD scanner?
Select “Read Codes” or a similar option on your scanner’s menu. The scanner will display any active and pending diagnostic trouble codes (DTCs). Note down the codes for further research and diagnosis.

Can you plug in OBD scanner while car is running?
While technically possible, it is generally not recommended to plug in or unplug an OBD2 scanner while the car is running. It is best practice to turn the ignition off before connecting or disconnecting the scanner to ensure safe and proper operation.