Modern vehicles are marvels of engineering, boasting significantly more control units than cars from the 1990s. This complexity means that a vast range of potential issues can be diagnosed simply by interpreting error codes. This is where on-board diagnostics (OBD2) scanners become invaluable.
Learning How To Use An Obd2 Scanner can empower you to save considerable time and money on car repairs. This guide provides essential information that every car owner should know about these diagnostic tools.
What is an OBD2 Scanner and What Does It Do?
An OBD2 scanner is a specialized tool designed to connect to your car’s computer system via a designated port, extracting crucial information from its control units. This data encompasses fault codes, which signal potential problems, and live data streams, providing real-time readings of various parameters like pressure, temperature, and speed.
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The information gathered by an OBD2 scanner originates from a network of sensors distributed throughout your vehicle. Fault codes typically arise when a sensor reading falls outside of its expected range or when a sensor ceases to respond. Think of it as your car’s way of signaling that something isn’t quite right.
More sophisticated diagnostic scanners offer advanced functionalities beyond basic code reading. These can include performing service resets, activating specific service procedures (like retracting brake calipers for pad replacement), and even vehicle coding, which is increasingly necessary when replacing electronic components in today’s cars.
The standardization of on-board diagnostics became mandatory for all cars manufactured in the United States from 1996 onwards and in Europe starting in 2004, making OBD2 scanners universally applicable to most modern vehicles.
Understanding Different Types of OBD2 Scanners
The market offers a wide array of OBD2 scanners to suit various needs and budgets.
The most accessible and budget-friendly option is a Bluetooth OBD2 code reader. These compact devices pair wirelessly with your smartphone, turning it into a diagnostic tool. Typically costing just a small amount, Bluetooth readers are capable of reading fault codes and displaying basic live data, making them a practical choice for everyday drivers seeking to understand basic car issues.
For individuals who are more inclined towards DIY car maintenance and repairs, investing in a more feature-rich OBD2 scanner is advisable. These scanners, often priced starting around $100 and upwards, not only read fault codes and live data but also offer the ability to reset service lights, initiate service functions required for tasks like brake pad replacement, and access a broader spectrum of live data parameters.
However, standard OBD2 scanners may fall short of the requirements of professional automotive technicians. Professionals need tools that can handle everything from routine maintenance like oil changes to complex engine repairs. For them, fault code reading and basic live data are just the tip of the iceberg compared to the extensive coding and programming capabilities found in professional-grade OBD2 diagnostic tools.
Equipped with the right professional tools, a skilled automotive electrician can fine-tune virtually every programmable option within a modern vehicle’s systems. These professional diagnostic systems, however, come with a significant price tag, often costing thousands of dollars, and their complexity makes them unsuitable for the average car owner.
Step-by-Step Guide: How to Read OBD2 Fault Codes
Reading fault codes is the foundational step in OBD2 diagnostics. Mastering this process is essential for anyone wanting to effectively use an OBD2 scanner. While the specific controls and interface may differ between scanner models, the underlying principles remain consistent.
1. Locate and Connect the Scanner
Every modern car is equipped with an OBD2 port. This port is typically located beneath the steering wheel column or within the center console area. It’s often concealed behind a small plastic cover, so you might need to look closely to find it. Once located, plug your OBD2 scanner firmly into the port.
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Many contemporary scanners and code readers utilize Bluetooth technology for wireless communication. If you’re using a Bluetooth scanner, ensure it’s properly paired with your smartphone or other device according to the manufacturer’s instructions.
2. Turn on the Ignition
Computer diagnostics via an OBD2 scanner require the car’s ignition to be switched on. Before initiating a scan, turn the ignition to the “ON” position. To minimize battery drain during the diagnostic process, it’s advisable to switch off unnecessary electrical loads like headlights, the radio, and the air conditioning system.
While most vehicles allow fault code scanning with the engine running, fault codes are stored in the car’s computer memory and will persist until intentionally cleared, regardless of whether the engine is on or off. However, starting the engine can be beneficial when you intend to examine live data readings, as certain sensor values are only generated when the engine is operating.
3. Vehicle Selection
Upon successfully connecting your OBD2 scanner and turning on the ignition, the scanner will typically prompt you to select your vehicle’s details, including make, model, and year of manufacture. This information is crucial for the scanner to correctly identify the car’s specific control units and accurately interpret the data it retrieves.
Many modern diagnostic tools incorporate an automatic vehicle identification system. This feature automatically detects the car’s VIN number (Vehicle Identification Number) and configures all the necessary vehicle-specific parameters automatically. Furthermore, you usually have the option to manually enter the VIN if the automatic identification fails for any reason.
4. Initiate Fault Code Scan
Finally, navigate the scanner’s menu to locate and select the fault code reading or scanning option. Most scanners provide flexibility, allowing you to choose to scan specific control units individually or to perform a comprehensive scan of all accessible control units in the vehicle.
If you encounter difficulty in locating these options within your scanner’s interface, consult the scanner’s built-in help section or refer to the user manual for step-by-step guidance.
The duration of a full system scan can vary depending on the car model and the number of control units present, ranging from a few seconds to several minutes.
5. Interpreting Fault Codes
The fault codes displayed after a scan are the key to understanding why warning lights may be illuminated on your dashboard. Sometimes, fault codes are quite explicit and straightforward, such as “00287 – ABS Wheel Speed Sensor; Rear Right.” In this instance, the code strongly suggests that the rear right ABS sensor needs replacement.
However, it’s important to recognize that the underlying causes behind fault codes are often more complex than they initially appear. For example, a seemingly simple code like “P0171 – System Too Lean (Bank 1)” indicates that the engine’s air-fuel mixture is too lean. While the code points to a lean mixture, the root cause could be any number of issues, including a clogged fuel filter, a failing fuel pump, a vacuum leak in the intake system, malfunctions in various sensors, or a multitude of other potential problems.
Pro Tip: Leveraging Live Data for Deeper Diagnostics
Beyond fault codes, the ability to access and interpret live data streams significantly enhances your diagnostic capabilities. Most control units within a car provide a dedicated section for live data, enabling you to monitor sensor readings and system parameters in real-time as the car is running. How can this be beneficial?
Consider a scenario where your car is exhibiting reduced power, and the only fault code present is a generic notification indicating that the vehicle has entered “limp mode” (a reduced power safety mode). In such a situation, live data becomes invaluable. You can use the scanner to monitor critical parameters like fuel pressure, turbocharger boost pressure (if applicable), intake airflow rate, and intake manifold pressure. By observing these live data values, you can often pinpoint whether these systems are operating within their normal ranges, helping to narrow down the potential cause of the limp mode and power loss.
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However, even with access to fault codes and live data, deciphering the information and effectively troubleshooting car problems can sometimes be challenging. Don’t hesitate to seek assistance from online resources, repair manuals, or experienced mechanics when needed.
OBD2 Scanners: A Must-Have for Used Car Buyers
The used car market, while offering opportunities for affordable vehicle ownership, also presents potential pitfalls for buyers. Unscrupulous sellers may attempt to conceal a car’s unfavorable history, pre-existing electrical problems, or even legal encumbrances.
While comprehensive vehicle history reports are invaluable in uncovering a car’s past, a thorough pre-purchase vehicle inspection is absolutely crucial to mitigate the risk of incurring substantial repair expenses shortly after buying a used car.
Before finalizing the purchase of any used vehicle, it’s always prudent to obtain a vehicle history report and, crucially, to scan the car for fault codes using an OBD2 scanner. If you don’t own an OBD2 scanner or are unsure about how to use an OBD2 scanner effectively, it’s highly recommended to take the car to a qualified professional mechanic for a pre-purchase inspection. This relatively small investment can save you from potentially costly surprises down the road.
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Clearing Fault Codes: What You Need to Know
Scanning for fault codes is an integral part of diagnosing car problems. However, fault codes themselves often don’t directly reveal the precise cause of an issue. Even when computer diagnostics point to a faulty component, such as a mass airflow sensor, experienced automotive technicians will typically perform further tests, often using a multimeter, to confirm the sensor’s malfunction before replacing it. This practice helps to rule out other potential causes and avoid unnecessary parts replacements. Surprisingly often, seemingly sensor-related fault codes can arise due to issues like damaged wiring, loose electrical connections, or corrosion within connectors.
Once the underlying problem has been identified and rectified, it’s essential to re-scan the car for fault codes to verify that the issue has been resolved. If the fault code no longer reappears after clearing it and performing a re-scan, it’s a strong indication that the problem has been successfully fixed, and you can confidently get back on the road.
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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 shoddy cars so he could spend time fixing, driving, and selling them. Evaldas is always interested in automotive technical innovations and is an active participant in automotive community discussions.
