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OBD2 adapter - functions, costs and tips

Anyone who is interested in cars has probably come across the term OBD2 adapter. It is needed when reading out the error memory, when coding and many other things. But what is the OBD2 adapter and how much does such a device cost? In this article we will show you tips, functions and costs related to the OBD2 adapter.

So what is an OBD2 adapter?An OBD2 adapter is required for the connection between the car and the diagnostic device or app. The functions depend on the diagnostic device / app itself and can range from a simple error code reading to coding on the vehicle. The costs are between 50 € for a simple device and several thousand euros for a professional device. However, these are usually only available for real workshops.

We wish you a lot of fun reading the text and hope that you will be well informed about the subject of OBD2 adapters afterwards.

On the history of OBD

First of all, the OBD standard should be explained in more detail. OBD is the abbreviation for on-board diagnosis. OBD2 refers to the second generation of the on-board diagnostic system.

All systems influencing exhaust emissions are monitored in a car while it is in motion. Likewise, all important control devices whose data are accessible to the workshops via a software interface. If there is a defect or abnormal behavior in a system, the driver receives information via a control lamp on the dashboard. The error itself is stored in the respective control unit. The error message can then be read out in a workshop via the standardized OBD2 interface. Not only the vehicle mechanics make use of the diagnostic system. For example, the TÜV uses it to control the exhaust gas values ​​of vehicles. But how long has OBD2 been around? More on that now!

The predecessor OBD1

The predecessor for OBD2 comes from the USA. In order to reduce the increasing air pollution caused by growing car traffic in metropolitan areas such as Los Angeles and San Francisco, the California Air Resources Board (CARB) introduced stricter emission limits for gasoline-powered vehicles in 1988. The demand for self-monitoring of the vehicles arose. The basis for this consideration was that "compliance" with the emissions regulations was no longer sufficient only when a vehicle was registered. The rules should be met for a lifetime. The OBD1 standard provided for electronic systems for self-monitoring to be installed in all vehicles. From now on, emissions-related errors also had to be made visible via a signal light on the dashboard and saved in a readable memory. Other US states adopted these regulations in 1994. The main disadvantage of the first on-board diagnostic system: It was not standardized. Each manufacturer developed and installed its own system. And even in the different vehicle models of the car manufacturers there were different systems. A uniform readout in the auto repair shops was therefore impossible.

OBD2 as standard

In 1994 CARB issued the regulation that all new motor vehicles from 1996 onwards must be equipped with the newly developed OBD2 system. In this way, not only the emissions regulations were monitored, but the entire exhaust-influencing system with the various processes in a vehicle. In addition, reading out the fault memory has been made easier via a standardized interface.

With the new emission standard EURO III, OBD2 was also introduced in Europe from 01/01/2000 (EOBD). Since then, emission errors have to be indicated by a warning light on the dashboard and the error codes recorded by the vehicle. Since 2001, the OBD2 interface has been a regulation for all vehicles with Otto engines (petrol engines). Since 2004 also for all diesel vehicles.

The new standard not only makes their work easier for car mechanics. This interface is also a blessing in private life. Most people drive to the workshop immediately when the engine indicator light flashes. That saves time and nerves, but it doesn't necessarily go easy on the wallet. Very few people know that there are now a large number of OBD2 adapters for private use to carry out an error analysis yourself with a reader or an app.

What is an OBD2 adapter?

An OBD2 adapter is a connection piece to a reader or a mobile app for troubleshooting and fault diagnosis on your own car. This is connected to the universal connection of the OBD2 system in the driver's area. These connections are often well hidden in the car or difficult to access. You can find out exactly where the interfaces are located in the respective vehicle models by searching the Internet. There are even apps and online services that know the answer.

What is the use of an OBD2 adapter?

After the OBD2 interface has been found and the OBD2 adapter connected, troubleshooting can begin. The ignition must be switched on for reading, but it is not necessary to start the engine. When the adapter is used for the first time, the attached reader or app is fed with the vehicle data. In rare cases with the identification number of the car. This is always in the vehicle registration document. Then the actual reading of the error memory takes place. The OBD2 adapter accesses the control unit and analyzes the data. Most of this data is not relevant in most cases. At the end, the device provides a list of error codes that are currently affecting the car and usually provide information about existing faults. In some cases the error code is ambiguous. In such cases it does not help and the workshop has to be visited.

Danger: With some adapters, the car's fault memory can not only be read out. There are now devices with which the error can be deleted and even codes can be selected. This work should really be left to the professionals in the car workshops or very experienced hobby mechanics. Before you know it, the entire control unit is blocked with an incorrect coding. The repair costs for this are in the four-digit range.

Which codes do OBD2 adapters read?

Unless there is a special OBD2 adapter from a certain manufacturer, the devices only read standard error codes for private use. Codes that all manufacturers use equally.

The error codes are structured according to a uniform principle: one letter and four numbers. Professional devices provide additional information about general damage, such as defective vehicle lights. These results are not displayed with a commercially available adapter. The error codes of these connectors only contain information from the sensors and electronics from the following areas:

  • Powertrain (Code "P" = Powertrain)
  • Chassis (code "C" = chassis)
  • Body (code "B" = body)
  • Networks (code "U" = User Network)

This is how you determine the location of the error. The second digit relates to the error code group.

  • 0 manufacturer-independent
  • 1 manufacturer-specific

The vehicle assemblies are in the third position.

  • 0 refers to the overall system
  • 1 stands for the secondary air / air mixture preparation
  • 2 is a fault in the fuel system
  • 3 concerns the ignition system / misfiring
  • 4 quantifies all additional systems for emission monitoring
  • 5 designates the cruise / idle speed control
  • 6 relates to the computer and its input / output signals
  • 7 stands for the transmission

The digits 4 and 5 are then the consecutive numbers of the individual components.

By the way: The OBD2 adapter not only reads errors, it also allows certain vehicle functions to be monitored. Which values ​​exactly depend on the respective vehicle and the diagnostic tool used. Some manufacturers even go so far as to allow live control of the car.

For example, depending on the car and OBD2 adapter, you will receive the following values ​​while driving:

  • the engine load in%
  • the cooling water temperature
  • the speed in rpm
  • the voltage in V
  • the fuel consumption per 100 kilometers
  • the gear in which the car is currently driving
  • the speed with currently valid speed limits
  • the outside temperature in ° C

Notes on error storage

When using the OBD2 adapter, it is helpful to know how the errors are stored in the car's error memory together with the environmental data.

  1. Only reproducible errors are transferred to the error memory. If it is no longer confirmed during a subsequent driving cycle, the first entry is deleted from the memory.
  2. Information and errors relevant to exhaust emissions are always saved. They are given priority one.
  3. A control lamp in the dashboard lights up in the event of successive emissions-related errors.
  4. If there is damage or impairment in the area of ​​the catalytic converter, the control lamp flashes.
  5. Exhaust-related errors are only automatically deleted from the error memory after 40 consecutive error-free journeys. In the catalytic converter area, the limit is 80 inconspicuous journeys.

Which OBD2 adapters are there?

There are now numerous versions of OBD2 adapters on the market. Either as a plug with an associated diagnostic device or in connection with a smartphone app.

OBD2 adapter with reader

The commercially available OBD2 connectors with a reader are widely used. You can read the error codes on the readers. However, the codes are not always clear and understandable. Here you have to consult the internet. The devices receive the necessary power supply via the OBD2 interface. Since the power consumption is very low, there is no need to worry about the vehicle battery.

OBD2 adapter with app

With the app analysis you need a special WLAN adapter or Bluetooth adapter to establish a connection to the smartphone. The error memory can then be read out via an app (e.g. Carly). The advantage here is obvious. Apps are much more complex and have more details and background information. In addition to the error codes, they also indicate the meaning and possible causes after the analysis. Some apps even inform you whether you have to go to a workshop with this error or whether it is safe to continue your journey. At the same time, it is possible to feed the on-board computer with external data. The OBD2 adapter with app works in both directions. Once to read errors or to feed in information and codes. The already mentioned OBD2 adapter from Carly is the most extensive in terms of the information displayed.

How much does an OBD2 adapter cost?

The costs for an OBD2 adapter are not to be mentioned as a flat rate of 20 euros. In addition to the device performance, the speed of analysis and the scope of diagnostics, the device equipment itself is also important. Is it an OBD2 adapter with a reader or one with an integrated WLAN or Bluetooth receiver for the smartphone? The range of functions also affects the price. Can the detected error code be deleted after the error analysis or not? Some OBD2 plugs are only suitable for analyzing the codes. Additional software, which in many cases costs extra, makes the exact codes recognizable. The built-in chip technology of the individual devices also affects the price.

Roughly estimated, most products are between 15 and 100 euros. Occasionally, adapters in connection with the smartphone incur additional costs for the app.

It should be mentioned that the market has grown a lot in recent years. Even high-end devices are now available for up to 5000 euros.

Now you might be thinking: Why should I spend money on a quick fault analysis? It can't be that much more expensive in a workshop.

What is the advantage of a fault analysis with an OBD2 adapter?

The pure error analysis costs around 30 to 50 euros in a workshop. In addition, there are individual expenses, depending on the problem and how quickly it can be resolved.

It is worthwhile to at least save the cost of fault detection. In the long term, buying an OBD2 adapter is always cheaper.

What should be considered when buying an OBD2 adapter?

1. Quality

It is best to pay attention to well-known manufacturers and to spend a few euros more before the rude awakening occurs when using the device. Test judgments on the Internet or qualified customer ratings are helpful in making a selection.

2. Updates

Pay attention to the availability of regular free software updates. They are a must to keep the adapter up to date.

3. Manufacturer

Occasionally it happens that the OBD2 adapter is not compatible with your own vehicle model. Make sure that the device can be used for your car. Ideally, it is not tied to one manufacturer, but can be used in a variety of ways. So you can still benefit from it after a car change.

4. Privacy

If the app variant is used, it makes sense to check data protection. Most apps save the read data on a server. The best are app providers who provide precise information about the processing of the data or whose servers are located in countries in which the General Data Protection Regulation applies.

5. Range of functions

You should only buy adapters that are able to read all generic error codes. At the same time, it should be possible to output a comprehensive error diagnosis. Pay attention to additional functions when purchasing, vehicle-specific devices can often do more than universal devices.

You have now learned a lot about OBD2 adapters. First you got a brief overview of the general terms OBD and OBD2 in connection with vehicles. Then we explained to you what an OBD2 adapter is, what is possible with it and which error codes it gives you. And last but not least, we showed you that in addition to OBD2 adapters with reading devices, there are also those with app control.

We'll go into this in more detail in the next section.

OBD2 apps and their advantages

With just a few clicks, your own smartphone becomes a diagnostic tool for the car. They look into the deepest part of the control unit and uncover errors without the car having to go to a workshop. With apps like Carly, Pace or RYD you save time and money.

Read-out apps don't just diagnose small defects. They also provide detailed information about vehicle errors and whether it is safe to continue your journey. OBD2 adapters with readers do not provide this information.

Readout apps, in a nutshell

  • Diagnostic apps read out a car's fault codes using a smartphone.
  • The car is accessed via the OBD2 port in the driver's area of ​​the car.
  • Connection via WiFi or Bluetooth using an adapter
  • Interpretation of the stored error codes by the app
  • Allow apps to delete error codes.

But anyone who thinks that they can simply access the controls of the car with their mobile phone is wrong. You need a "mediator" as a liaison between the cell phone and the car: the OBD2 adapter or dongle already described. It transmits the data via a cable or via a Bluetooth or WLAN connection.

Some read-out apps require the adapter from the respective app manufacturer. This is usually available in a finished package. So-called universal apps are also on the market. These do not require an extra manufacturer adapter, but work together with everyone. However, their reliability is nowhere near as high as that of a complete system. The apps also differ greatly from one another. While some only offer fault selection, there are also manufacturers who use their app to provide diagnostics and even useful safety information. One of these apps is the Carly app.

The Carly app

Like a diagnostic device, Carly reads the error codes from the control unit and provides information on how to rectify them or on safety instructions. You can even delete error codes.

For a fault diagnosis, the Carly adapter is connected to the OBD2 connection in the car and connected to your own smartphone and the Carly app via BLE (Bluetooth Low Energy). The Carly adapter is suitable for both iOS and Android operating systems and supports many different vehicle brands: BMW, Mini, Skoda and many more.

Note: Carly only works in conjunction with the Carly adapter.

FAQs Carly adapter for the Carly app

  • Where is the Carly adapter priced?
    • The adapter costs EUR 59.90 and the app costs between EUR 21 and 80, depending on the version.
  • Which operating systems / smartphones are supported?
  • Which vehicle models and brands are covered by this?
    • Carly supports BMW, Seat, Skoda, Toyota, Volkswagen, Lexus and Mini
  • Is there a return policy?
    • You can return the adapter within 30 days

Here is an overview of the various functions of the Carly app:

Additional functions of the Carly app

In addition to diagnosis, the app allows various functions to be coded and some special functions to be activated. With Carly you can recode your lighting setting and change the brightness levels and flashing intervals.Optical or acoustic signals on the vehicle can be set with it, as well as different warning signals, such as B. a seat belt reminder. Clean the car dashboard yourself + 2 more tips for saving money

Drivers of diesel vehicles will find the "DPF diagnosis" function very interesting. This allows the status of the diesel particulate filter to be read out and manual regeneration of the DPF to be initiated. Cars with Otto engines have a similar function for the NOX catalytic converter. Depending on the vehicle model, the exhaust flaps can be controlled manually.

A special feature is the used car check within the app. Unfortunately, it happens again and again that odometer readings have been manipulated when selling used cars. Together with the OBD2 adapter, the app reads the mileage from the built-in control units and checks whether the mileage information from the speedometer matches the information from the various control units. This makes manipulations easily recognizable.

With this app you also have the option of checking or observing certain vehicle parameters on your mobile phone while driving: oil temperature, fuel pressure, etc.

The app's “Digital Garage” also saves various vehicle data, the error history, maintenance intervals, etc. in a completely clear and comprehensible manner at all times.

The Carly app in a nutshell

With the Carly app you can make a "deep diagnosis" of your vehicle and the fault memory. The Carly app contains numerous features that are otherwise only implemented in professional devices.

  • Activation of hidden functions
  • Reset maintenance interval
  • Checking and manual regeneration of the diesel particulate filter
  • Similar function for NOX catalytic converters
  • Read out and delete error codes
  • Uncover speedometer manipulation (used car check)
  • Follow engine parameters live

Conclusion OBD2 adapter

You have now learned a lot about the subject of OBD, OBD2 and OBD2 adapters. In summary, it can be said that buying or using an OBD2 adapter is a sensible thing. However, they should be used with a certain sense of proportion and require a basic understanding of technology. You should also always pay attention to the legal regulations for adapters and apps that allow recoding of vehicle specifics. Which variant you choose is up to you. If it does not go beyond pure error readout, an adapter with a reader is probably suitable. If, in addition to the error code, you also want information on troubleshooting, assessing driving safety with certain errors or even making changes to the car, then we recommend using an app, such as the Carly app presented. In addition to an app for reading errors, they offer many additional functions that would have to be paid for every time you visit the workshop for setting or changing them.