Modern vehicles are incredibly complex, packing in numerous control units compared to cars from the 1990s. This complexity, however, comes with a silver lining: the ability to diagnose a wide range of issues simply by reading error codes. This is where using an OBD2 scanner becomes invaluable.
Learning how to use an OBD2 scanner can save you significant time and money on car repairs. Here’s a comprehensive guide on everything a typical car owner needs to know about these powerful diagnostic tools.
What is an OBD2 Scanner and What Does It Do?
An OBD2 scanner is a diagnostic tool that connects to a special port in your car and retrieves data from its control units. Think of it as a translator, allowing you to understand what your car’s computer is trying to tell you. This data includes crucial fault codes and real-time information, known as live data, such as pressure, temperature, and speed readings from various sensors throughout the vehicle.
Mechanic using an OBD2 scanner to diagnose a car
All this information originates from sensors monitoring different systems within your car. Fault codes typically appear when a sensor reading falls outside the normal range or when a sensor stops responding altogether. These codes are often the reason why your check engine light or other warning lights illuminate on your dashboard.
More advanced OBD2 diagnostic tools go beyond simply reading codes. They can perform various service functions, such as resetting maintenance reminders, and even coding, which is necessary when replacing certain components in today’s sophisticated vehicles.
On-board diagnostics became standardized and mandatory for all cars manufactured from 1996 in the United States and from 2004 in Europe, ensuring broad compatibility and access to this diagnostic technology.
Understanding Different Types of OBD2 Scanners
The market offers a wide variety of OBD2 scanners to suit different needs and budgets.
The most basic and affordable option is a Bluetooth OBD2 code reader. These compact devices pair with your smartphone via Bluetooth and, when used with a compatible app, can read fault codes and display basic live data. Typically costing just a small amount, Bluetooth scanners are a convenient entry point for average drivers wanting to understand their car’s basic health. However, their capabilities are usually limited to basic diagnostics.
For those who are more inclined towards DIY car repairs, investing in a more capable handheld OBD2 scanner is advisable. These scanners, often priced starting around $100 and upwards, offer more advanced features. Beyond reading fault codes and live data, they can reset service lights, activate service functions needed for tasks like replacing brake pads, and access a wider range of live data parameters.
Professional automotive technicians require tools that can handle any situation, from routine maintenance to complex repairs. While standard OBD2 scanners are useful, they pale in comparison to the extensive capabilities of professional-grade OBD2 diagnostic tools. These advanced systems offer features like coding and programming, allowing for deep-level adjustments and configurations within a vehicle’s electronic systems.
With the right professional tools, an experienced automotive electrician can fine-tune virtually every customizable option in a modern car. However, these sophisticated tools come with a significant price tag, often costing thousands of dollars, and their complexity makes them unsuitable for the average user.
Step-by-Step Guide: Using Your OBD2 Scanner to Read Fault Codes
Reading fault codes is the fundamental step in OBD2 diagnostics. If you want to effectively use an OBD2 scanner, learning this process is essential. While the specific controls may vary depending on the scanner model, the general procedure remains consistent.
1. Locate the OBD2 Port
Every modern car is equipped with an OBD2 port. It’s typically located beneath the steering wheel, often in the driver’s side footwell area, or sometimes in the center console. The port may be hidden behind a small plastic cover, so you might need to look closely to find it. Once located, ensure easy access to plug in your OBD2 scanner.
Diagram showing the typical OBD2 port location under the steering wheel in a car
For wireless scanners or code readers that utilize Bluetooth, ensure proper pairing with your smartphone or device is established according to the manufacturer’s instructions.
2. Turn on the Ignition
Computer diagnostics require the car’s ignition to be switched on. Before proceeding with scanning, turn the ignition to the “ON” position. This provides power to the car’s computer systems without starting the engine. To minimize battery drain during the diagnostic process, it’s advisable to turn off unnecessary electrical loads like headlights, the radio, and the air conditioning.
While many vehicles allow fault code scanning with the engine running, initiating the scan with just the ignition on is generally sufficient for reading stored fault codes. Fault codes are saved in the vehicle’s computer memory and will remain until you intentionally clear them. Starting the engine might be more relevant when you intend to monitor live data readings immediately after scanning.
3. Choose Your Vehicle
After connecting your OBD2 scanner and turning on the ignition, the next step is to identify your vehicle to the diagnostic tool. This typically involves selecting your car’s make, model, and year. This information is crucial for the scanner to correctly recognize the car’s control units and accurately interpret the data.
Many modern diagnostic scanners are equipped with an automatic VIN recognition feature. This system automatically detects the car’s VIN number and automatically configures the necessary vehicle information. This streamlines the setup process. If, for any reason, the automatic VIN recognition fails, you usually have the option to manually enter the VIN.
4. Scan for Fault Codes
With the vehicle identified, you can now initiate the fault code scan. Navigate through the scanner’s menu to find the fault code reading or diagnostic scan option. Most scanners offer choices to scan specific control units individually or to perform a comprehensive scan of all available control units.
If you encounter difficulties locating these options, consult the scanner’s built-in help section or refer to the user manual provided with the device. These resources should offer clear guidance on navigating the scanner’s interface and initiating a scan.
The duration of a full scan can vary depending on the car’s model and the number of control units it has, ranging from a few seconds to several minutes.
5. Inspect Revealed Fault Codes
The fault codes displayed after the scan are the key to understanding why warning lights may be illuminated on your instrument panel. Some fault codes are quite explicit and easy to understand. For example, a code like “00287 – ABS Wheel Speed Sensor; Rear Right” strongly suggests that the rear right ABS sensor needs replacement.
However, it’s important to understand that fault codes often point to a potential problem area, and the actual underlying issue can be more complex than the code initially suggests. For instance, a common code like “P0171 – System Too Lean (Bank 1)” indicates that the engine’s air-fuel mixture is too lean. While the code identifies the symptom, the root cause could be a variety of issues, such as a clogged fuel filter, a failing fuel pump, a vacuum leak, malfunctions in various sensors, or other potential problems within the fuel or air intake systems.
Pro tip: Reading Live Data
The ability to read live data is an invaluable asset in diagnosing complex car problems. Most control units within a vehicle provide a live data section in diagnostic tools, allowing you to monitor real-time readings from various sensors and systems as the car is running. How can this be helpful?
Consider a scenario where your car is experiencing a noticeable loss of power, and the only fault code present is a generic “limp mode” notification. In this situation, live data can provide crucial insights. You can monitor parameters like fuel pressure, boost pressure (for turbocharged engines), intake airflow, and intake manifold pressure in real-time. By comparing these live readings to expected values, you can pinpoint anomalies and narrow down the potential causes of the limp mode and power loss.
Close-up of an OBD2 scanner displaying live data readings during car diagnostics
However, remember that even with access to fault codes and live data, accurately diagnosing and resolving car problems can sometimes require expert knowledge and experience. Don’t hesitate to seek professional help when needed to properly interpret the data and identify the correct repair steps.
OBD2 Scanners: An Essential Part of Used Car Buying
The used car market can present challenges for buyers. Unscrupulous sellers may attempt to sell vehicles with hidden problems, ranging from undisclosed accident history to electrical malfunctions and even legal issues.
While obtaining a vehicle history report is a smart step to uncover a car’s past, a thorough vehicle inspection is paramount to avoid unexpected and costly repairs after purchasing a used car.
Before finalizing the purchase of any used vehicle, it’s always recommended to get a history report and, importantly, to 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 a wise investment to take the car to a trusted mechanic for a professional pre-purchase inspection. This inspection should include a comprehensive OBD2 scan to identify any potential hidden issues.
Check your VIN
Avoid costly problems by checking a vehicle’s history. Get a report instantly!
How to Get Rid of Fault Codes
Scanning for fault codes is a crucial step in diagnosing car problems, but fault codes themselves rarely pinpoint the exact solution directly. Even when computer diagnostics indicate a faulty mass airflow sensor, experienced automotive technicians will typically test the sensor using a multimeter to confirm its malfunction before replacing it. This verification step is essential to avoid replacing parts unnecessarily, as fault codes can sometimes be triggered by related issues like damaged wiring, loose connections, or corrosion, rather than a faulty sensor itself.
Once the underlying problem has been identified and repaired, it’s necessary to clear the fault codes from the vehicle’s computer memory. After clearing the codes, it’s important to rescan the system to ensure that the fault codes do not reappear. If the codes remain clear after the repair, it’s a good indication that the problem has been successfully resolved, and you can confidently get back on the road.
Frequently asked questions
Evaldas Zabitis
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.
