Does Car Have to be Running to Use OBD2 Scanner?

Does Car Have to be Running to Use OBD2 Scanner?
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When the check engine lights come on, it is time to connect your OBD2 scanner to see what is going on. This scan tool will help display certain engine codes, which can be found in the user manual, so you can see what is wrong.

But do you need to run your car’s engine before you have access to the diagnostic system? The quick answer is no; you only need to turn on the ignition, so there is power available for the scanner.

But that is not all there is to it. Read on to push the power button and find out how to use it and what you can and can’t do.

What Is an OBD2 Scanner?

Many people are confused with the code scanner and the code reader and get the two mixed up most of the time. The scan tool is a far more advanced piece of equipment with a wide variety of functions, while the reader has only basic features.

The basic features you have with the reader are recording and displaying live data and resetting the check engine light. It also provides you with an option to clear the trouble code that is displayed, and a user manual is included to explain every trouble code to avoid confusion.

You can get a code reader for just over $20 dollars, and anyone can use it to see what the problem is with their car. On the other hand, an OBD2 scanner will cost you anything from $100 to close to $1000 and is difficult to use.

An OBD2 scanner can provide you with the codes and a textual display of what that code means and how to rectify the error. It also comes with the basic functions you find in a reader and is equipped with diagnostic features to run a full diagnostic.

Scanners are mostly used by professional mechanics to run a diagnostic on your vehicle when there are errors to help fix them. The diagnostic trouble codes, which are displayed as live data on the scanner, help them to determine why the check engine light is on.

All vehicles are equipped nowadays with an OBD2 connector, which can be found below your car’s steering column. By using an OBD2 scanner, experts can use the live engine codes to find the problem and fix it quickly and easily.

There are many different scanner models available that come with a wide range of features. Cheap scanners come with basic features and some extra functions, while more expensive ones come equipped with advanced diagnostic scanners built into them.

A scanning tool that comes included with a diagnostic tool will cost more than scanners that do not have it included in the package.

What Can You See With an OBD2 Scanner?

One of the main features found on a code scanner is the fuel system to see what is your car’s overall fuel consumption. It can also look at the fuel mixture to see if the fuel and oxygen levels of the mixture are correct for your vehicle.

This is also one of the reasons why your check engine light may come on and can easily be fixed by professional mechanics. The malfunction indicator light on the vehicle can mean many different things that range from timing belts to serious errors.

Meanwhile, the code scanner can provide you with the correct reason for what is wrong with your vehicle and provide a solution. 

How To Use an OBD2 Scanner

Here are the easy steps to use your code scanner when your check engine light is on to see what is wrong.

  1. Have your owner’s manual ready at hand
  2. With your vehicle powered down, connect the OBD2 scanner by plugging it into the diagnostic port located below the steering column 
  3. If you have a self-powered scanner, you can switch it or turn the ignition to the on position to power the scanner
  4. Use care when you plug it into the port because the pins can easily bend and distort, and then you will have no connection.
  5. When you turn the ignition on and power the scanner, wait for it to boot up
  6. Wait for it to establish a connection and follow the instructions on the display
  7. After the boot process is completed, you need to supply the scanner with the necessary data
  8. The data you need to supply will include the VIN number, model and make of your car, and the type of engine
  9. It is time to start the actual scanning, so hit the button reserve and wait until it is finished scanning
  10. The codes displayed will tell you what types of errors were found during the scan
  11. Now that you have the codes, you can start to take the necessary steps to rectify the errors

Make sure you have your manual on hand to search for the code so you can see what is wrong with your vehicle. You can also search for these codes and the definition of each online. This way, you may find the problem and solution among the many answers.

See the following Youtube video for full instructions on how to use a code scanner or code reader quickly and easily.

Different Types Of Code Messages

Each problem code may start with a letter, and they all have different meanings. We will take a look at some of them.

P: For Powertrain

The P codes occur the most, and they have to do with a wide range of problems, such as the fuel system and emissions. It also covers the ignition system and other general problems that may occur.

B: For Body

Error codes starting with a B indicate any problems you may have with the seatbelts and other types of seat sensors. It also covers power seating errors and the airbags, and, in general, all types of problems that occur inside the vehicle cabin.

C: For Chassis Code

These error codes will cover everything that can go wrong with the mechanical part and mechanisms of the vehicle. This will have to do with the brakes systems, the steering, and the car’s suspension.

Can a Code Scanner Or Reader Work With All Vehicles? 

Most code scanners come fitted with a universal connector attached to them so they can be used with all types of vehicles. Unfortunately, some code scanners and readers will only fit on certain vehicles, but they are not many.

mechanic man with diagnostic scanner at car shop

Can Anyone Use a Code Scanner Or Reader?

Code Readers

When it comes to code readers, anyone with a little bit of tech-savvy will be able to use them with any type of vehicle. These code readers will display basic codes when you use them to help determine the problem when the check engine light comes on.

If you can read the trouble codes, you can use the reader, which will be very beneficial for DIYers.

Code Scanners

Code scanners, on the other hand, will display the enhanced codes used by professional mechanics, and only they will understand them. Code scanners are also the best option to use when you want to apply code clearing, so the check engine will be reset.

Scanners are also much more efficient than the bare-bones code readers found on the market. However, they are also more expensive. Because of the advanced features and functions on scanners, they are also more accurate, especially the high-end versions and models.

When it comes to functionality, the code scanner can, apart from clearing codes, also reset MILs and run complete diagnostics on your engine.

Types Of Code Scanners

There are so many different models of code scanners to be found on the market that it is sometimes difficult just to choose one. They come with great features included, with many different connection options to make them easier to use.

Some of the features include a Bluetooth connection option or even an easy and fast Wi-Fi connectivity for easy access. The newest trend is an app you can download onto your smartphone and connect it with the OBD2 connector. This will do most of the basic scans you may find on a reader or scanner.

Features Of a Code Scanner

The following is a list of functions that can only be found on code scanners.

  • You can easily reset the oil light with a scanner
  • It can also read and reset the codes that occur for the brakes
  • Live data displayed on the scanner can be used there and then to rectify most problems
  • Some of the more expensive code scanners provide you with an interactive dashboard

Must Your Vehicle Run When You Use An ODB2 Scanner?

As mentioned in the intro, it is not necessary to run your vehicle if you want to do basic scanning for codes. When you run it, you can see live data, which will help you determine what is wrong with your car.

Specific tests need to be performed in order for you to see live data to make an informed decision.


Thanks to advanced technologies, it is possible for anyone to understand the codes on your reader or scanner and follow the instructions in the user’s manual. But it is best to leave the diagnostics to the experts if it looks to be a bit daunting for you to understand.


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