Modern vehicles are technological marvels, boasting significantly more control units than cars from the 1990s. This advancement means that diagnosing car problems has become more accessible than ever, often starting with simply reading error codes. This is where On-Board Diagnostics 2 (OBD2) scan tools come into play, empowering car owners to understand their vehicle’s health.
Learning how to use an OBD2 scanner can save you considerable time and money on car repairs. This guide provides everything a typical driver needs to know to effectively use these tools for car diagnostics.
Understanding OBD2 Scanners
What is an OBD2 Scanner and What Does it Do?
An OBD2 scanner is a valuable device that connects to a specific port in your car, acting as a communicator with your vehicle’s computer system. An OBD2 scanner is a tool that plugs into your car’s OBD2 port to retrieve data from its control units. It gathers information such as diagnostic trouble codes (DTCs), also known as fault codes, and real-time data, including readings of pressure, temperature, and speed from various sensors throughout the vehicle.
This information originates from a network of sensors within the car. Fault codes typically appear when a sensor reading goes outside the normal range or if a sensor stops responding altogether, indicating a potential issue.
More sophisticated diagnostic scanners offer advanced functionalities, such as performing service resets and even coding. Coding is particularly essential when replacing certain components in newer cars that require electronic configuration to function correctly with the vehicle’s system.
The implementation of OBD2 systems became mandatory for all cars manufactured in the United States from 1996 and in Europe from 2004, making it a universal standard for vehicle diagnostics.
Types of OBD2 Scanners
The market offers a wide array of OBD2 scanners to suit different needs and budgets.
The most basic and affordable option is a Bluetooth OBD2 code reader. These compact adapters pair wirelessly with your smartphone via Bluetooth. Typically costing just a small amount, they can read fault codes and display basic live data, making them an excellent, user-friendly choice for everyday drivers.
For those who prefer to handle their car maintenance and repairs, investing in a more capable OBD2 scanner is advisable. A more advanced scanner can reset maintenance lights, activate service functions needed for tasks like brake pad replacement, and access a broader range of live data parameters. These scanners generally start at around $100, with prices increasing based on their features and capabilities.
However, standard OBD2 scanners may not meet the extensive demands of professional mechanics. Professionals require tools that can handle everything from routine tasks like oil changes to complex procedures such as engine replacements. Reading fault codes and basic live data is only a fraction of what professional-grade OBD2 diagnostic tools can do.
Professional OBD2 diagnostic tools offer extensive coding and programming capabilities. With the right professional tools, a skilled automotive technician can fine-tune virtually every configurable option in a modern vehicle. However, these advanced systems are complex and can cost thousands of dollars, making them unsuitable for the average car owner.
Step-by-Step Guide: How to Use an OBD2 Scan Tool
Reading diagnostic trouble codes (DTCs) is fundamental to OBD2 diagnostics. If you intend to use an OBD2 scanner, learning this process is the crucial first step.
While the controls can differ between various OBD2 scanner models, the fundamental procedure remains largely consistent.
Step 1: Locate the OBD2 Port and Connect the Scanner
Every modern car is equipped with an OBD2 port. This port is usually located beneath the steering wheel or within the center console area. The OBD2 port is often concealed by a small plastic cover, so you may need to look closely to find it. Once located, plug your OBD2 scanner securely into the port.
Many newer scanners and code readers utilize Bluetooth technology, eliminating the need for physical wires. If you’re using a Bluetooth scanner, ensure it is properly paired with your smartphone or device.
Step 2: Turn on the Ignition
Computer diagnostics cannot be performed if the car’s ignition is off. Therefore, before initiating a scan, turn the ignition to the “ON” position. To minimize electrical load during the diagnostic process, it’s advisable to turn off unnecessary accessories like headlights, radio, and air conditioning.
Most vehicles allow fault code scanning while the engine is running. Fault codes are stored in the vehicle’s computer memory and will persist until manually cleared. However, starting the engine can be particularly useful when monitoring live data readings from various sensors.
Step 3: Vehicle Selection
Once the OBD2 scanner is connected and the ignition is on, the next step is to identify your vehicle to the scan tool. You’ll typically need to select your car’s make, model, and year. This information is vital for the scanner to correctly recognize the vehicle’s control units and accurately interpret the data.
Many contemporary diagnostic tools feature an automatic VIN recognition system. This system automatically detects the car’s Vehicle Identification Number (VIN) and configures the necessary vehicle information for you. If automatic VIN detection fails, you can also manually enter the VIN into the scanner.
Step 4: Scanning for Fault Codes
After vehicle identification, navigate the scanner’s menu to find and select the fault code reading option, often labeled as “Read Codes” or “Trouble Codes.” Most scanners offer the option to scan specific control units or perform a comprehensive scan of all available control units.
If you are unsure how to proceed, consult the scanner’s built-in help section or the user manual for detailed instructions on locating these options.
The duration of a full system scan can vary from a few seconds to several minutes, depending on the car model and the number of control units.
Step 5: Interpreting Fault Codes
The fault codes revealed after the scan are the underlying cause of warning lights appearing on your dashboard. Sometimes, fault codes are relatively self-explanatory, like “C0031-04 – Right Front Wheel Speed Sensor – Circuit Open.” This code directly suggests a problem with the right front wheel speed sensor.
However, the actual issues behind fault codes are often more complex than they initially appear. For instance, a common code such as “P0171 – System Too Lean (Bank 1)” indicates that the engine’s air-fuel mixture is too lean. This problem could stem from a variety of causes, including a clogged fuel filter, a failing fuel pump, a vacuum leak, faulty sensors, or other issues within the fuel or intake systems.
Advanced Tips: Reading Live Data
The ability to read live data is a powerful feature that significantly enhances your diagnostic capabilities. Most control units within your vehicle have a live data section accessible through the OBD2 scanner, allowing you to monitor sensor readings in real-time as the car is running. How can this be beneficial?
Consider a scenario where your car feels underpowered, and the only fault code present is a generic “limp mode” notification. By examining live data, you can check critical parameters such as fuel pressure, boost pressure (for turbocharged engines), intake airflow, and intake manifold pressure. Deviations from normal values in these readings can pinpoint the source of the problem more effectively.
However, even with access to fault codes and live data, diagnosing car problems can still be challenging. You may need to consult repair manuals, online forums, or seek professional advice to accurately interpret the data and identify the root cause of the issue.
OBD2 Scanners and Used Car Inspections
The used car market can present risks for buyers. Unscrupulous sellers may attempt to sell vehicles with hidden histories, electrical faults, or even legal encumbrances.
While vehicle history reports provide valuable background information, a thorough pre-purchase inspection is crucial to avoid unexpected and costly repairs.
Prior to buying any used vehicle, it is always recommended to obtain a vehicle history report and, importantly, check for fault codes using an OBD2 scanner. If you don’t own an OBD2 scanner or are unsure about how to use one effectively, it’s wise to have the car inspected by a qualified professional mechanic before making a purchase.
Check Your VIN
Avoid potential problems down the road by verifying a vehicle’s history. Get an instant report today!
Clearing Fault Codes: What to Know
Scanning for fault codes is a step in diagnosing car problems, but fault codes themselves often don’t directly reveal the exact issue. Even if a diagnostic scan indicates a faulty mass airflow (MAF) sensor, experienced technicians will typically test the sensor with a multimeter to confirm the fault before replacing it. Surprisingly often, fault codes can arise from issues like damaged wiring, loose connections, or corrosion, rather than a faulty sensor itself.
Once the underlying problem is identified and repaired, it’s essential to re-scan for fault codes to ensure the issue is resolved. If the fault code no longer appears after the repair, the problem is likely fixed, and you’re good to drive.
Frequently Asked Questions
(Note: The original article includes an “FAQ” section which is empty. In a real article, this section would be populated with common questions related to OBD2 scanners. For this rewritten article, I will omit the FAQ section as per the instructions to maintain close similarity to the original and focus on the core task.)
Article by
Evaldas Zabitis
Evaldas has been writing since middle school and has had a passion for cars for as long as he can remember. Right after getting his driver’s license, he spent all of his savings on less-than-perfect cars so he could dedicate his time to fixing, driving, and selling them. Evaldas maintains a keen interest in automotive technical innovations and actively participates in discussions within the automotive community.
