Using an ELM327 Bluetooth Scan Tool for Android and PC

Use your PC or phone to scan your vehicle's OBD-II system diagnostics

ELM327 Bluetooth devices provide an easy way to scan a vehicle's Onboard Diagnostics II (OBD-II) system for codes. They can also read PIDs and aid in diagnostics. These devices represent a low-cost way for DIYers and seasoned techs alike to tackle computer diagnostics. However, there are a few ELM327 Bluetooth-related issues you need to be aware of before you buy one.

Potential Problems

The most pervasive issue with ELM327 Bluetooth devices is that some low-cost scanners include unauthorized ELM327 microcontroller clones. These cloned chips often exhibit strange behaviors, but even legitimate hardware fails to work with certain devices. If you want to use an iOS device as a scan tool, it's especially important to pay attention to these issues.

An electronic diagram of a brain with speedometers in the brain

alengo / E+ / Getty Images

ELM327 Bluetooth Compatible Hardware

Scan tools that include an ELM327 microcontroller and a Bluetooth chip are capable of pairing with a variety of devices, but there are some important limitations. The primary devices you can use an ELM327 Bluetooth scan tool with are:

  • Smartphones
  • Tablets
  • Laptops

The most convenient way to take advantage of ELM327 Bluetooth connectivity is to pair a scanner with a phone, but not all phones work well with the technology. The primary exceptions include Apple iOS products such as the iPhone, iPad, and iPod touch.

These iOS devices typically don't work with ELM327 scanners due to the way that Apple handles the Bluetooth stack. Most generic ELM327 Bluetooth devices fail to pair with Apple products, which means that Apple users are better off with USB and Wi-Fi ELM327 scanners.

In some cases, other smartphones can have issues pairing with certain ELM327 Bluetooth scanners. This is typically due to problems with unauthorized, cloned microcontrollers that don't have an up-to-date code.

Pairing ELM327 Bluetooth Devices

Aside from the situations outlined above, pairing ELM327 Bluetooth devices with smartphones, tablets, and PCs is typically a simple procedure. The most common steps are:

  1. Plug the ELM327 Bluetooth device into the OBD-II port.

  2. Set the smartphone, tablet, or laptop to scan for available connections.

  3. Select the ELM327 scan tool.

  4. Input the pairing code.

In most cases, the documentation that comes with an ELM327 Bluetooth scanner includes the pairing code and special instructions that differ from that basic outline. If no documentation is included, try one of the common codes, which include:

  • 0000
  • 1234
  • 6789
  • 9999

If those codes don't work, other sequential sets of four numbers are sometimes used.

What to Do When Pairing Fails

If your ELM327 Bluetooth scanning device fails to pair with your smartphone, there are several potential causes. The first step is to try alternate pairing codes. After that, pair the scanner with a different device. Some faulty cloned ELM327 microcontrollers have trouble connecting to certain devices, and you may find that your scanner pairs with a laptop while it refuses to connect to your phone.

Another thing that can cause a failed pairing is the limited amount of time your scanner remains discoverable. Most ELM327 Bluetooth scanners become discoverable as soon as you plug them in, but they stop being discoverable after a specific amount of time. If you perform the pairing operation within one minute of plugging the scan tool into the OBD-II jack, there shouldn't be an issue.

If your scan tool still doesn't pair, the unit may be faulty. This is the primary reason that it's a good idea to stay away from cheap, cloned scanners. Buy a scanner from a retailer that stands behind its products.

ELM327 Bluetooth Alternatives

The alternatives to ELM327 Bluetooth scanners are devices that use Wi-Fi and USB connections. Wi-Fi ELM327 scanners are typically more expensive than devices that use Bluetooth, but they can be used with Apple products. Most USB ELM327 scanners aren't designed for use with Apple products, but some Apple-authorized options can be used with the dock connector.

Was this page helpful?