Understanding OBD-II Scanners

YOUCANIC • 13 December 2019

An OBD-II scanner, allows you to read and clear Diagnostic Trouble Codes (also known as fault codes, DTCs) on vehicles 1996 and newer.

Your dealer and mechanic use OBD-II scanners to diagnose most of the problems with today's vehicles.  While the scanners used at the dealership are the most advanced and expensive, aftermarket scanners are readily available for DIYers who want to troubleshoot their own vehicles. 

Which OBD-II scanner should I buy? 

Entry-level OBD-II (OBD-2) scanners start at about $20 but can only diagnose the check engine light.

On the end are the professional scanners that can go over $1000 and will be able to read, clear and program any module in any car. 

To help you choose the best OBD-2 scanner, we divide scanners into three categories. 

  1. Level 1 - Basic Code Readers, Least Expensive, Can only read and clear codes from the Engine Control Unit (ECU). 
  2. Level 2 - Multi-system OBD-2 Scanner, Can read and clear codes from Engine, Transmission, ABS, Airbag. Depending on the scanner it may be able to read and clear codes from other modules such as climate control, suspension, charging system, etc. 
  3. Level 3 - Professional OBD-2 Scanners, Professional Level, These scanners offer similar functionality to what the dealer uses. They can read, clear, program, view live data and activate all systems in your car. 

We hope that after reading this article, you will have a better understanding of OBD-2 scanners. When it comes to OBD-2 scanners, there is no one size fits all solution. A key component here is how much you are trying to spend on a scanner and whether you want it to work on only one make or many vehicle models.

When buying an OBD-2 scanner ask yourself these questions: 

  1. What are you trying to diagnose?

    • Check Engine Light,

    • ABS Problems

    • Airbag / SRS Light

    • Transmission Problems

    • Program Modules

  2. What is your budget? 

  3. Do you need a scanner to work on one make (example BMW) or multiple makes? 

Level 1 OBD-2 Scanners

basic obd2 scanner

These basic OBD-2 scanners, (also known as code readers or generic OBD-2 scanners), retrieve data from the Engine Control Unit (ECU).

You can retrieve Diagnostic Trouble Codes (DTC) (also referred to as fault codes) that trigger the Check Engine Light and Service Engine Soon

Level 1 scanners don't access other modules besides Engine Control Unit (ECU) or provide any coding capabilities.

Simply plug into the OBD-2 port and read the code. They show you a fault code. A few scanners even tell you what the code means. Regardless of what description you get from the scanner, write down the code and do online research to understand what are common problems with your make.

Capabilities

Here is a list of what you can do with these scanners:

  1. Read Fault Codes from Engine Control Unit

  2. Determine why Check Engine Light is on. 

  3. Erase Check Engine Codes

  4. View Freeze Frame Data

  5. Display live sensor data from ECU

Limitations

  • It can not access other modules.

  • Can not read codes from ABS, SRS, transmission, etc. 

  • Can not troubleshoot TPMS

  • No programming or coding

Most Level 1 scanner sell for under $100. Typically can only diagnose the Check Engine Light or Service Engine light.

Many of these scanners can display live sensor data that the Engine Control Unit controls. Level 1 OBD-2 scanners cost as little as $15. Every car owner must at a minimum have one of these cheap OBD-2 scanners in the glove box.  

Level 1 OBD-II Scanners

ANCEL AD310 Classic Enhanced Universal OBD II Scanner Car Engine Fault Code Reader CAN Diagnostic Scan Tool - Black

ANCEL AD310 Classic Enhanced Universal OBD II Scanner Car Engine Fault Code Reader CAN Diagnostic Scan Tool - Black

TT TOPDON TD300 OBD2 Scanner Code Reader with Engine Light Turn-Off

TT TOPDON TD300 OBD-2 Scanner Code Reader with Engine Light Turn-Off

BAFX Products Bluetooth Diagnostic OBDII Reader

BAFX OBD2 Products Bluetooth Diagnostic OBDII Reader

BlueDriver Bluetooth Professional OBDII Scan Tool for iPhone, iPad & Android

BlueDriver Bluetooth Professional OBDII Scan Tool for iPhone, iPad & Android

Veepeak Mini WiFi OBD2 Scanner Compatible with iOS and Android, Car OBD II

Veepeak Mini WiFi OBD2 Scanner Compatible with iOS and Android, Car OBD II 

Level 2 Multi-System OBD-2 Scanner 

level 2 obd2 scanner

Level 2 scanners (also referred to as a multi-system OBD2 scanner) are slightly more expensive but their main advantage is that they allow you to read and clear fault codes from many modules.

If you work on cars frequently or are trying to troubleshoot problems other than the check engine light, you need a multiple system OBD-2 scanner.

These scanners not only can reset the check engine light but they can read and clear codes from various modules including Anti-Lock Brakes, Airbag system, Transmission, and Tire Pressure Monitoring System, etc.

A number of multi-system scanners only read and clear codes from the engine, transmission, abs and airbag modules, while a full system OBD-2 scanner will be able to read, clear and reset fault codes from almost all of the modules on the vehicle.

A full system OBD-2 scanner is the way to go if you work on cars frequently. One trip to the dealer could save you enough money to buy one of these scanners. 

Even if you haven't used a full system OBD-2 scanner before don't worry. They are very easy to use and function the same as the basic OBD-2 code readers. The main difference is that they can access another system in your car, not just the ECU. 

One of the popular scanners in this category is the Launch Creader Multi-System Scanner

Capabilities

  • Read/Erase Check Engine Codes

  • Read/Erase ABS Fault Codes

  • Read/Erase Airbag / SRS Codes

  • Troubleshoot transmission problems

  • View Sensor Live Data

Limitations

  • No Coding

  • No Programming

  • One-directional communication

Level 3 Professional Diagnostic Scanners

professional level scanners

Professional diagnostic scanners provide similar functionality to the scanners used at your car dealerships. These are meant for mechanics that operate auto repair shops.

If you are a DIYer and can afford a professional diagnostic scanner, you may never need to go to the dealer or mechanic. Level 3 diagnostic scanners are expensive with the majority of the scanners ranging between $1000 and $3000.

Level 3 scanner offer bi-directional support and can diagnose all system and control units.

A complete system expert scanner is not limited to one make but works on most car brands including Honda, Toyota, BMW, VW, Mercedes, Porsche, Ford, Chevrolet, etc. Bi-directional supports allow you to activate, program and test sensors and systems in your car. 

These are professional scanners and are more expensive. These professional OBD-2 scanners are often used by auto mechanics and offer full system diagnostics.

We have included a few that are easy to use by mechanics and car owners who can afford one. Level 3 OBD-2 scanners offer a bi-directional function which means that you can activate and test various sensors on the car.

Many car manufacturers require that certain modules can only be coded by the dealer. Professional scanners will not be able to code the replacement of certain modules if the coding can only be completed by the dealer. 

Popular Level 3 Scanners