What is ELM327 scanner and how to use it

2024 Author: Malcolm Clapton | [email protected]. Last modified: 2023-12-17 03:44

Find out how to diagnose a car yourself and save on car services.

What is ELM327

The ELM327 designation is familiar to many car owners. This is a scanner or adapter that connects to the on-board computer of the car via the OBD-II connector. A useful device is used to diagnose malfunctions, read performance indicators and reset ECU (electronic control unit) errors.

The scanner got its name from the name of the microcontroller, which is a kind of link between the diagnostic bus of a car and a computer or smartphone. This chip developed by a Canadian company fell into the hands of Chinese electronics manufacturers, who did not miss the chance to copy it.

What does the ELM327 scanner do

The functionality of the ELM327 is quite extensive. But it largely depends on the support of certain capabilities by a specific version of the adapter, the ECU of the machine itself, as well as the software that is used for diagnostics.

In addition to reading, decoding and clearing diagnostic error codes, the scanner is able to display in real time the engine speed and speed of the car, the temperature of all liquids, the current fuel and air consumption, the position of the throttle valve, the pressure in the fuel system and much more.

In some cars, using the ELM327 adapter, you can unlock and reconfigure the automatic locking and folding of the mirrors, the responsiveness of the gas pedal, the dashboard data.

How to choose ELM327

Due to the many clones of different quality, there is a risk of running into a device with reduced functionality, which will not work correctly or will not start at all. There are three important points to consider when buying.

1. Connection type

There are several versions of ELM327 with different connection interfaces. The most common are adapters with Bluetooth, Wi-Fi and USB. They differ not only in connectivity, but also in compatibility with smartphones and computers. The rest of the functions are identical.

• Bluetooth are the cheapest scanners that only work with Android smartphones.
• Wi-Fi - more expensive versions, compatible with both Android and iOS smartphones and computers.
• USB is slightly cheaper than Wi-Fi scanners. They work only with computers, but they differ in the reliability of communication.

2. Firmware version

Adapters software is constantly updated. On the original ELM327, the current version is already 2.2. Chinese clones are sold with firmware 1.5 and 2.1. Oddly enough, the more recent version is worse.

The chip that got to the Chinese had firmware version 1.5. All clones with this firmware have the original ELM327 software. Later, copies of scanners version 2.1 appeared. The latter is only a modified firmware 1.5, and not for the better - to reduce the cost of production, the Chinese have removed many communication protocols. In addition, there are regular adapters with version 1.5 that are sold under the guise of 2.1.

In fact, three versions of ELM327 clones are now on sale:

• ELM327 1.5 - old but original firmware;
• ELM327 2.1 - stripped-down original firmware under the guise of a newer one;
• ELM327 2.1 - original firmware disguised as new, but no changes.

Obviously, it is worth buying an adapter with the original firmware version 1.5. For example, here is one of the trusted sellers from whom you can buy an inexpensive one.

3. Type of auto diagnostic connector

For some cars, especially before 2000 and domestic ones, the diagnostic connector has pads of other standards. Connecting a scanner to them directly will not work. For such cases, special adapters are used: on the one hand, they have a compatible connector for a specific car model, and on the other, a standard OBD-II.

Proprietary pads can have a different shape and number of contacts. Therefore, before buying a scanner, check which connector standard is used on your car, and, if necessary, purchase the appropriate adapter.

How to check the ELM327 scanner

After purchasing the ELM327 adapter, check that it is actually version 1.5. When ordering from AliExpress, check if the PIC18F25K80 chip is installed in it and emphasize that you will diagnose the scanner with special software and open a dispute in case of problems.

1. External examination

It is not so easy to visually identify a quality adapter. Opaque or dark plastic housing makes it impossible to inspect components. Their diminutiveness and hard-to-read markings complicate matters even more.

If you carefully open the case, you can take a look at the ELM327 boards. Look closely at all parts and look for a processor with the code PIC18F25K80. Firmware 1.5 requires just such a chip, so its presence will be a certain quality guarantee.

2. Application tester

A special application tests compatibility with the diagnostic bus protocols and shows the real version of the scanner. To check, do the following.

1. Insert the ELM327 adapter into the car diagnostic socket and turn on the ignition.
2. Open the Bluetooth or Wi-Fi settings on your smartphone and pair with the adapter (password: 0000 or 1234).
3. Install the application for testing and click the "Connect" button.
4. Wait for the scan to finish and check the results.
5. Successful work with most car brands is guaranteed if the adapter supports all revisions up to 1.4 or 1.4b inclusive.

How to connect to a car

The exact setup procedure is usually described in the instructions.

Step 1. Installing the Diagnostic Application

Various programs are used to connect to the computer's ECU. There are both free and paid versions for Android, iOS and Windows. Included with the scanner itself, the necessary software is often already included in the kit. Install it or one of the popular apps.

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Step 2. Connecting ELM327

The connector for the ELM327 adapter is located differently in cars. Usually somewhere under the steering wheel or in the glove compartment, but in some older models it may also be under the hood. Check how it is in your car and connect the scanner.

Step 3. Pairing devices

Next, you need to turn on the ignition and establish a connection between the scanner and a smartphone or laptop. If the adapter has a start button, remember to press that button as well.

Activate Bluetooth or Wi-Fi in the gadget settings and wait until the nearby devices are found. Choose ELM327 adapter: usually called OBDII. Connect to it. Use the code 0000 or 1234 to pair.

Step 4. Application configuration

Run the installed diagnostic application. Typically, the adapter type is automatically detected. If this does not happen, open the application settings, specify the connection type (Bluetooth, Wi-Fi or USB) and select an available scanner from the list.

How to use the ELM327 scanner

If everything is done correctly, after the setup, information about the car will be displayed on the screen, and the sensors and indicators will work. Depending on the application, you may need to create an auto profile. To do this, select your model from the list and indicate the technical characteristics.

Now you can view the performance of the engine and various systems, read ECU errors and reset them. The apps have corresponding buttons for each function. For example, in the most popular Torque utility these are "Dashboard", "Reading errors", "Graphs" and others.