How To Use An OBD2 Scanner

Using an OBD2 scanner is not that complicated. Here is an easy guide on how to use an OBD2 scanner to keep track of your vehicle’s diagnostics.

Here are the highlights:

  • OBD2 scanners allow users to scan a vehicle’s onboard diagnostics, revealing valuable data like engine RPMS, fault codes, fuel usage, etc.
  • Using an OBD2 scanner is not complicated. For a basic scan, you’ll only need to plug the scanner into your car’s OBD port and follow the on-screen prompts.
  • After collecting error codes, you’ll need to interpret their meaning. Some scanners offer full fault code details. If yours doesn’t, you’ll have to research them yourself.
  • Ultimately, having an OBD2 scanner is a must for any car owner. You will save money on car repairs, especially if you DIY troubleshoot and repair.

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OBD2 Code Scanner: Explained

Diagnostics of car failures: an electrician in gray clothes is sitting in the car's interior and reading the trouble codes from a portable auto scanner with OBD2 interface.

An Onboard Diagnostic II Scanner (OBDII/OBD2) is a hand-held device that plugs into a vehicle’s OBD2 port and returns critical data like engine RPMs, fuel usage, error codes, and more.

This beginner’s guide to using an OBD2 scanner focuses on reading and interpreting error codes for troubleshooting car problems, like when a Check Engine or Service Engine Soon light displays.

Taking into account that stores generally apply a $50 to $100 diagnostic fee, and a good OBD2 scanner is priced below $100, it is an incredibly useful instrument for any vehicle proprietor—once you understand how to utilize it.

How do you use an OBD2 scanner?

Follow these five simple steps:

  • Step 1. Locate OBD2 port
  • Step 2. Connect OBD2 scanner
  • Step 3. Enter vehicle data
  • Step 4. Scan for error codes
  • Step 5. Collect codes and unplug

If you’re mechanically savvy, the above instructions may be all you need to quickly scan your car for error codes. If you’d prefer a few more details, this guide explains each step further.

Additionally, we’ll answer some frequently asked questions about OBD2 scanners, including:

  • Do car error codes clear themselves?
  • How much does an OBD2 scanner cost?
  • Can you damage your car using an OBD2 scanner?
  • Can you read codes with the car off?

Let us begin.

How To Use An OBD 2 Scanner

OBD2 Scanner

Note: Most OBD2 scanners work similarly, but the exact steps and their user-friendliness vary between devices. Think of navigating an old flip phone vs. a contemporary touchscreen. Regardless, follow the on-screen instructions, and you should be fine.

Step 1. Locate OBD2 Port

All vehicles from 1996 onwards have an OBD2 port, usually located below the driver’s-side dashboard under the steering column. Look for a rectangular 16-pin connector, possibly with a cap.

Step 2. Connect OBD2 Scanner

To connect an OBD2 scanner, press the plug into the OBD2 port, much like a wall outlet. Follow the on-screen prompts. You may be asked to turn the key to the “accessory” position or start the engine.

Step 3. Enter Vehicle Data

Some OBD2 scanners ask for specifics about your car, like its VIN number or model type, while others automatically detect any necessary data. Follow the on-screen instructions until you are in the main menu.

Step 4. Scan For Error Codes

At the main menu, select “Read Codes.” Note that the exact wording depends on the scanner. If an error is detected, you’ll receive a unique five-digit code that starts with a letter.

Step 5. Collect Codes And Unplug

OBD2 scanners simply provide diagnostic data. They cannot repair issues. Gather the error codes, turn the key to the off position (when prompted), and unplug the scanner from the OBD2 port.

Understanding OBD2 Error Codes

OBD2 Scanner

Some OBD2 scanners have a built-in error code library giving details on each fault. If your scanner model is more basic, you’ll have to interpret the codes yourself.

All OBD2 error codes have five characters, consisting of a letter followed by four numbers, like P1234.

The first character is a letter indicating which primary vehicle system is prompting the error code.


  • P (Powertrain): Engine, emissions, transmission, etc.
  • B (Body): ABS, AC, airbags, etc.
  • C (Chassis): Steering, suspension, brakes, etc.
  • U (Undefined): Problems not categorized as P, B, or C

The second character is a number that tells if the issue relates to all vehicle makes (0) or if it’s manufacturer-specific (1).

The third character can be a number (0-9) or a letter (A-F) and points to the affected subsystem.


  • 0 = Emission controls
  • 1 = Fuel and air metering
  • 2 = Injector circuit
  • 3 = Ignition or misfire
  • 4 = Auxiliary emission control
  • A, B, C = Hybrid specific

The fourth and fifth characters can also be numbers or letters, are hexadecimal, and reveal more information about the fault.

Using P0011 as an example, we see that the problem lies somewhere in the powertrain, pertains to all makes, and involves the vehicle’s emissions.

The final two numbers, 11, may be described on your OBD2 scanner’s screen, depending on the model. Otherwise, you’ll have to review a trouble code book or search online.

Here’s an example of what you might see using a basic OBD2 scanner: P0011 – Intake Camshaft Position Timing – Over-Advanced (Bank 1). With this information, it wouldn’t take too much research to compose a list of potential causes.

In this case, P0011 often means a stretched timing chain or bad VVT solenoid, both of which are not particularly difficult repairs for a dedicated DIYer.

Ultimately, you could save $150 to $1,000 to resolve the above error code, all thanks to using an OBD2 scanner to troubleshoot and repair the issue yourself.

OBD2 Scanners: FAQ

Do Car Error Codes Clear Themselves?

Check Engine or Service Engine Soon lights from an OBD error code usually reset themselves after 10 to 20 cycles. A “cycle” can mean turning the key on/off or driving for a period of time. You can also manually reset a car fault code using an OBD2 scanner.

How Much Does An OBD2 Scanner Cost?

According to review sites like Tomsguide, Cnet, Amazon, and others, you can find a decent OBD2 scanner for $50 or less. Users preferring more features (Bluetooth, visual interface, fault code details, repair instructions, etc.) will find better options for around $200.

Can You Damage Your Car Using An OBD2 Scanner?

No, using an OBD2 scanner will not harm your vehicle, as the device merely collects data. However, note that some scanners can reset error codes. It is possible to harm your car if you continually reset fault codes without addressing the problem.

Can You Read Codes With The Car Off?

No, you can’t scan for new error codes with the engine off. You must start the engine to see live vehicle data, reset fault codes, and more. Regardless, follow your OBD2 scanner’s on-screen prompts for the best experience.

OBD2 Scanner: A Must For Any Car Owner

Used correctly, an OBD2 scanner will reduce vehicle repair costs, especially if you fully troubleshoot problems and repair them yourself.

Did you know you can also track a car using your phone and its OBD2 port? Check out our detailed guide for more info.

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Joshua Barrett

Josh Barrett is a writer hailing from the great state of Alaska. While describing himself in the third person is not his forte, writing about any and all things automotive – is. After 13+ years hustling in the exciting world of car sales, he took off to travel the world with his dog Teemo.