Better than ELM327 adapters: klavkarr Bluetooth OBD2 scanners

What is an ELM327 OBD2 scanner?

Several types of OBD adapter are available for car diagnostics. The most common are based on a chip from ELM Electronics.

The ELM327 is the most common and supports all the main OBD protocols: ISO 9141-2, KWP, PWM, VPW and CAN. Other ELM chips support a more limited range of protocols.

What types of ELM327 OBD2 adapter are available?

To our knowledge, there are 4 types of ELM327 interface:

Despite appearances, these 4 types of adapter are very similar electronically. Their main differences are the casing and connection type. They all use an ELM327 chip, so equivalent, correctly implemented adapters provide the same diagnostic functions.

Which adapter works with which device?

How can I check the ELM327 firmware version?

OBD adapter quality varies. The reported firmware version is not always reliable: some devices claim versions that the chip manufacturer never released.

• GENUINE VERSIONS: 1.0, 1.1, 1.2, 1.3, 1.3a, 1.4, 1.4b, 2.0, 2.1, 2.2 and 2.3
• NOT GENUINE VERSIONS: 1.2a, 1.4a, 1.5 and 1.5a, and any version not listed under "GENUINE VERSIONS".

What matters is checking what your adapter can actually do. Follow this procedure to test its capabilities.

1. Connect to your vehicle using our EOBD Facile software.
2. Open the console tab and enter the commands in the table below.
3. If the interface replies "OK", the command is supported. Otherwise a "?" will appear meaning the command is unknown.
4. Important: after this test, reset the connection before continuing to communicate with your vehicle.

Commands for checking that your ELM327 works correctly

Where can I buy an ELM327-compatible OBD adapter?

Our official klavkarr store

Many users asked where to buy an ELM327-compatible OBD2 adapter, so we developed our own klavkarr diagnostic scanner. It supports the latest ELM327 version (v2.3) and is made entirely in France.

• Every klavkarr scanner includes a licence for our EOBD Facile car diagnostic software.
• klavkarr scanners are in stock and are shipped by Colissimo within 24 hours.
• Our klavkarr adapter is easy to install and requires no computer expertise: it is plug and play.
• klavkarr is type-approved under UN Regulation No. 10 for automotive electromagnetic compatibility.

Buying an ELM327 adapter from abroad

Most sellers are based in China, Hong Kong or the USA. Before buying, we recommend you check the following:

• Check the software included: it is often only a limited demonstration version.
• Check whether the price includes any customs duties or additional VAT, particularly when buying from outside the European Union.
• Check the delivery method. If you are away during the day, consider postal delivery.
• Check whether the seller will replace or refund the device if it fails.

How to use an ELM327 adapter

1. Installing ELM327 drivers

• RS232: no installation is required.
• USB: install the adapter's USB driver to connect it to your computer.
• OBD Bluetooth: pair the adapter with your computer before use.
• OBD2 Wi-Fi: configure your computer's wireless network settings. See the EOBD Facile software help file for details.

2. First connection to the vehicle

1. Connect the interface to your vehicle's OBD connector. If you do not know where it is, see our page where is my OBD2 port?
2. Run the EOBD Facile software.
3. Switch on the vehicle's ignition. The check engine light on the dashboard should come on.
4. Click on Connect. The software will automatically connect to the vehicle.

3. Description of LED indicators

• Power (red LED): indicates that the interface is powered on.
• Tx OBD (yellow LED): flashes when data are sent from the interface to the vehicle.
• Rx OBD (green LED): flashes when data are sent from the vehicle to the interface.
• Tx USB (yellow LED): flashes when data are sent from the PC to the interface.
• Rx USB (green LED): flashes when data are sent from the interface to the PC.

Tip: on some interfaces, there are no labels on the indicators. In this case, when you power on, the red LED lights first followed briefly by Tx OBD, Rx OBD, Tx PC then Rx PC.

Cannot connect to your OBD2 adapter?

How can you check that your ELM327 OBD adapter works correctly?

Sometimes a connection to an OBD2 adapter cannot be established. Follow these steps to test your Bluetooth, Wi-Fi or USB ELM327 adapter with EOBD Facile.

Installing and using an ELM327 with EOBD Facile

You may encounter problems after installing your Bluetooth OBD adapter, Wi-Fi adapter or USB adapter. For example, your computer may have the wrong drivers. The video below explains how to install the correct driver.

Installing the right driver for your ELM327 on Windows

Important: drivers are specific to your ELM327 OBD adapter, not to EOBD Facile software. If the drivers do not work, contact the company that sold you the adapter.

If your ELM327 adapter does not power on, there may be a problem with the power supply at the OBD port. The video below shows how to check it with a multimeter.

Testing the voltage of your OBD2 port with a multimeter

Connecting your car to EOBD Facile

First, plug your ELM327 into the OBD2 port. Then connect it to EOBD Facile using the connection supported by your OBD2 adapter: Bluetooth, Wi-Fi or USB.

Once your vehicle is connected, open the Interface tab, then Interface settings in the desktop version. In the mobile app, go to Control unit, then Interface.

Understanding the settings

Once your vehicle is connected, open the Interface tab, then Interface settings. A new window shows your ELM327 adapter's details, including its version. Select Test.

After selecting Test

A progress bar appears in the desktop version, or a progress circle in the mobile app. This is normal: the software is connecting to the vehicle through your ELM327.

When the connection is established

On a computer, the software lists commands that failed. These may be required or optional. If any required commands fail, EOBD Facile will not work correctly and you will need to replace your ELM327. Missing optional commands do not affect the software's normal operation.

On Android or iPhone, required commands are shown in red and optional commands in white.

Bluetooth or Wi-Fi: which should you choose?

How a Bluetooth ELM327 OBD adapter works

Bluetooth ELM327 adapters use a wireless module instead of the cable used by USB and RS232 versions. Standard Bluetooth 3.0 adapters using RFCOMM do not normally work with iPhone or iPad. Bluetooth Low Energy adapters, using technology introduced with Bluetooth 4.0, can work with iOS when supported by the app. Classic Bluetooth adapters generally require pairing before first use, often with PIN 0000 or 1234; Bluetooth Low Energy adapters usually connect directly through the app.

How a Wi-Fi ELM327 OBD adapter works

Wi-Fi ELM327 adapters replace the USB cable with a wireless connection. Once plugged into the vehicle, the adapter creates a Wi-Fi network for communication. This network does not provide internet access, and you must disconnect from your current Wi-Fi network to join it. A password may be required, commonly 12345678.

Which ELM327 adapter should you choose?

ELM circuitry for electronics specialists

If your ELM interface breaks down or if you want to create your own circuit, the diagrams below will help you. They show the circuit of an ELM327 RS232 interface. The basic circuit is always the same whatever the connection mode (RS232, USB or Bluetooth): the difference lies mainly in the components connected to pins 17 and 18 of U1, the ELM327 integrated circuit.

USB ELM327 adapters use a USB-to-serial bridge with a virtual COM port (VCP) driver. Two common families are FTDI's FT232 (see the FTDI website) and Silicon Labs' CP210x (see the Silicon Labs website).

Bluetooth interfaces use an RS-Bluetooth modem; Wi-Fi interfaces use an RS-Wi-Fi modem.

Click on the images to enlarge

In the event of malfunction: ELM Electronics has created a very useful application note with the voltage levels and a test procedure.

Operating principle of the ELM327 interface

The electronic unit contains 3 main sub-assemblies to operate the interface:

• Voltage-level interfacing: vehicle networks use voltage levels that require dedicated transceivers. Because the ELM327 supports several protocols, it needs several interface circuits. These fall into three groups: CAN, K/L lines and PWM/VPW. See the communication standards page for details.
• The ELM327 chip: the integrated circuit, which gives its name to the whole device, is the brains of the interface.
• Computer-side voltage-level interfacing: the chip cannot communicate directly with a computer port, so an appropriate interface circuit is required.

This explains the term "interface": an ELM327 bridges two different environments, automotive electronics, where robustness and cost are important, and computing, where modularity is a priority.

Other types of interfaces

Only ELM interfaces are supported by our software, but other companies have developed interfaces with similar functions, for example Ozen Elektronik and their myOBDics interfaces. There are also professional products (Clip, Lexia…), which are far more expensive and work only with a single manufacturer group.