ELM327 – What is it, How to Find the Key Code & Pair it?

ELM327 scan tool is a car diagnostic scanner used to read and clear trouble codes. In this article, we explain what it is, how to find the key code and pair it

Elm327 Bluetooth Pin Code Reader

When the Check Engine Light comes on, your heart naturally sinks as you start figuring out what might be wrong. Thankfully, with an ELM327 Bluetooth scan tool, you can quickly pinpoint what’s wrong and get it repaired. 

In this article, we take a closer look at what the ELM327 device is. We also show you how to find the key code and pair it for quick use.

What is the ELM327 Bluetooth Scan Tool?

The ELM327 Bluetooth scan tool connects to your vehicle’s OBDII system to determine what’s wrong. It uses your compatible device to read the trouble codes from your engine’s computer. This information is transmitted to your device with the help of Bluetooth.

This tool replaces the traditional code scanner and is less expensive. However, it isn’t going to read as many codes as the professional scanner does. It also appears to have limited capability. 

How to Find ELM327 Key Code

Your ELM327 Bluetooth device includes a pairing code, along with the instructions needed to connect the equipment. If you are unable to find the pairing code, you might try a generic option instead. The most commonly used with the ELM327 device is 1234. Some other key codes that are commonly used include:

  • 1234
  • 0000
  • 1111
  • 9999

If you can’t get the codes to work, you might need to reach out to support. You could also attempt some other sequential sets of numbers. 

How to Pair ELM327 Device

1. Check OBDII Compatibility

Not every car is OBD2 compatible. This standard was only used in vehicles that are model year 1996 or later.

If your car is compatible, you want to find the OBDII diagnostic port. It is generally found under the steering wheel on the left-hand side. 

2. Install Device

Plug the ELM327 scanner into the diagnostic port. It won’t work with the car ignition off, so you need to turn it on.

Turn the key in the ignition to the 2nd spot. This keeps the engine off but provides power to the accessories, including the OBDII port. 

3. Connect to Device

On your Android device, you want to pair to the ELM327. Choose “Settings” and “Wireless & Networks.” From here, you will click on “Bluetooth Settings.” After you turn on the Bluetooth compatibility, the system will scan for any nearby devices.

You can pair your device with the scanner. Just look for the name of the scanner in the list and connect to it. At this point, you will need the key code we previously discussed. It should be 1234, but there are times when it is different. Once the device is paired, you are ready to read the trouble codes and start diagnosing your system.

ELM327 Bluetooth Compatibility

ELM327 devices aren’t compatible with all devices. In general, you can expect it to work with most Android smartphones, tablets and laptops. However, the Bluetooth scanners aren’t normally compatible with Apple iOS devices, such as the iPod Touch, iPad or iPhone.

Apple utilizes Bluetooth stack differently than the Android devices, making it more difficult to use the ELM327. The majority of these ELM327 devices will fail to pair along with your Apple product. If you have an Apple device, you might do better with the Wi-Fi or USB ELM327 scanners.

If you are still having trouble getting the Bluetooth connected with what should be a compatible device, there’s an issue with the microcontroller. Some devices contain an unauthorized and cloned microcontroller that doesn’t exhibit an updated code. 

ELM327 Pairing Fails – What to Do Next

If the ELM327 Bluetooth device fails to pair with your device, there are several possible reasons. In some cases, you might be able to get it paired.

For starters, try another pairing code. We listed the most used codes above, but you might need to reach out to support if this is giving you trouble.

If that’s not the problem, you want to try a different device to pair it with. If you can pair it with another device, the ELM327 scanner isn’t the problem. Sometimes, a faulty cloned ELM327 scanner fails to connect with particular devices. It’s common to have the device connected to a laptop but not a phone.

The other issue is how long the Bluetooth scanner is discoverable by your device. When it is first plugged in, it shows up in your list of devices. However, it will only be discoverable for a certain amount of time after that. If you attempt to pair it after time has elapsed, you might have trouble finding it again. The simple solution to this problem is to unplug it from the OBDII port and plug it back in. Try again immediately after putting it back into the port.  

If you still can’t get the devices paired to one another, your ELM327 scanner might be faulty. Remember, the device is on the inexpensive side, so it’s not uncommon for things to go wrong. For this reason alone, some people choose to buy a professional scanner, especially if the codes need to be read more often. If this scanner gives you trouble, you might consider returning it and getting something more reliable. 

ELM327 Bluetooth Scanner Alternatives

If you aren’t happy with the ELM327 Bluetooth scanner or it doesn’t work with your device, there are other options available to you. For starters, there are ELM327 scanners that rely on USB or Wi-Fi connections.

You are going to spend more on the Wi-Fi scanner because of the sophisticated technology. However, these are the best type to use if you have an Apple device. If you choose to go with an ELM327 USB device instead, keep in mind that this might also be incompatible with your Apple product. However, you might be able to use a dock connector to get a solid signal. 

On the other hand, you could also upgrade to a better device overall. Consider the benefits of using a professional code scanner if you are doing regular work on car engines and systems.

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Magnus Sellén
Written by:

Magnus is the owner and main author of Mechanicbase. He has been working as a car mechanic for over 10 years, and the majority of them specialized in advanced car diagnostics and troubleshooting. Certified Automotive Diagnostic Technician.