What is a Code Reader for Cars: Vehicle Diagnostic Tools Explained
A car code reader, also called OBD-II scanner, is a vehicle diagnostic tool that reads out fault codes in your car. A fault code is a short-hand description of a potential issue your car may be facing. Each fault code will direct you towards a specific car part and the source of the issue.
Car code readers work by scanning the on-board diagnostic (OBD) system. Almost all vehicles manufactured after 2001 will have an OBD system, which is used to monitor performance through various sensors.
An OBD scanner is often thought of as something only professionals, car manufacturers, and auto mechanics use. Code readers, however, have gotten significantly more accessible and now usually include integrations with mobile apps, making them more valuable to regular car enthusiasts.
How car code readers work
All code readers link up with the OBD system within a car for which the port is somewhere within the reach of the driver such as under the driver’s side steering column dashboard. The onboard diagnostic computer is actually always measuring and collecting data, however, it’s mostly not available until some issue is detected.
For example, when the check engine light appears on the dashboard, that’s triggered by the onboard diagnostics. As many car enthusiasts know, however, the check engine light can mean a great deal of things and point to numerous issues.
Most car mechanics will use an OBD scanner to retrieve the error codes and evaluate their severity. Almost all OBD2 error codes are publicly available and can be found on various blogs and websites.
Some OBD scanner providers, however, acquire licenses from car manufacturers and include manufacturer-specific trouble codes. For example, our own OBD2 scanners provide extensive diagnostics for VAG and BMW automobiles while also including regular OBD2 trouble codes for most other brands from 2008.
So, the car code reader simply connects to the existing OBD port and extracts the data that has been stored. Depending on the car code reader type, it will then either simply output the trouble code or provide additional information such as descriptions and vehicle performance data.
Some tools may also provide various remapping and tuning features, mostly for the Engine Control Unit (ECU). Most of these tools will be targeted towards advanced users and may require secondary tools.
Types of car code readers
While there are uncountably many minor differences between car code readers, most can be separated into categories based on the device itself and the features provided.
1. OBD2 diagnostic scanners
A basic OBD2 scanner will usually be a device that connects to the OBD port. They were created with the intention to reduce and control vehicle emissions, so most of the features provided are related to only the relevant parts (engine, transmission, etc).
Primarily, a basic OBD car code reader will let you check engine codes, retrieve live vehicle data, and perform emissions tests. They can also clear codes if required.
Most of the basic car code reader displays will have a simple screen with a few buttons. Nothing too fancy, but great for someone just getting into vehicle systems and scan tools in general.
2. Advanced diagnostic scanners
More advanced OBD2 scan tools will have all of the features of a basic code reader, but also include car manufacturer code reading and, potentially, some coding capabilities.
Advanced scanners can monitor all electronic systems and control units, which is the primary upgrade from regular diagnostic scanners.
In most cases, the possibility to read manufacturer-specific fault codes is the major selling point for advanced OBD2 scanners. These are often not only more descriptive and specific, but also cover systems that are not covered by regular OBD2 diagnostics, making it easier to detect and diagnose issues. Finally, they can clear OBD2 and other codes.
These code readers are a fairly large upgrade from the basic version, but are still completely viable to a regular user.
3. Dealership diagnostic tools
These diagnostic tools are created by car manufacturers themselves and are generally inaccessible to the general public. Usually, only authorized repair services can utilize these diagnostic tools.
Dealership diagnostic tools are a major upgrade from any OBD2 scanner. They not only inherit all of the capabilities, but get a lot of manufacturer-specific features. Most of these tools are capable of connecting directly to manufacturer databases and servers.
These capabilities mean that dealership diagnostic tools can be used not only for diagnostics and programming, but they can also upgrade car firmware, restore factory settings, and even unlock additional paid features.
Finally, these tools may provide various set up protocols, repair instructions, and various other quality-of-life features.
Common uses of car code readers
Of all the uses for OBD scanners, acquiring diagnostic information is by far the most popular. Even the simplest ones can help you check engine trouble codes, often guiding you towards the solution to potential issues.
Those that also function as a Bluetooth scanner, while they still connect to the diagnostic port, located under the steering wheel, the associated mobile applications can provide even greater diagnostic accuracy.
A wireless scanner can often retrieve data from many systems and collect it to an easy-to-understand dashboard. All of the logistical and driving data helps users pinpoint potential issues with greater ease.
Some of the wireless OBD readers may come with verified fixes for common problems, making problem resolution easier for less experienced users.
There are some additional use cases, outside of pure diagnostics. For example, most OBD scanners will allow you to clear fault codes, reset the check engine light, and run an oxygen sensor (emissions) test.
On the other hand, full-system and bi-directional scan tools can reprogram most of the car’s computer system. Professional users can do a lot of things, ranging from basic maintenance and diagnostics to improving the performance of the car.
Finally, more advanced can also perform Control Unit coding, which is essentially turning on or off certain features. These may be automatic door locking or automated daytime light switching.
Choosing the best scanner
The primary decision driver will be your experience, maintenance needs, and overall enjoyment when tinkering with cars. If you’re looking for something that would explain the check engine lights, a simple car code reader will do.
If you want to run more extensive tests, tinker with the data from engine sensors, you’d likely need at least an advanced OBD scanner.
Mechanics and repairmen may require full-system scan tools to do the job well, especially if it involves modifying the vehicle settings in any way. A simple OBD scanner may be enough if all that needs to be done is clearing the check engine light.
In general, car enthusiasts and beginners alike will find the most value in a more advanced diagnostic tool that has Bluetooth connectivity, an associated application, and a user-friendly interface.
A simple, old-school scanner that only connects to the OBD port and displays trouble codes might not be enough.
The simplest OBD readers will also be slightly more difficult to use for less experienced people. Trouble codes aren’t that easy to read without external help and, even then, may be too vague to point out specific issues. Most low-budget diagnostic tools lack a user-friendly interface, which may make them harder to utilize.
Advanced OBD readers will not only usually provide more extensive descriptions for trouble codes, but also let you view data or freeze frames, which makes pinpointing the exact issue easier even without experience.
Additionally, the price differences between these two won’t be as immense while the quality of life provided by advanced OBD readers will be worth every penny.
So, car enthusiasts, beginners, and non-professional mechanics will often do best with an advanced OBD reader. Mechanics and professionals may require more advanced solutions like full-system scan tools.