This guide describes the process of connecting the Android app to a Bluetooth ELM327 adapter.
On the app's main screen, the Bluetooth indicator in the top-right corner (to the left of the car icon) blinks during connection. After successful connection, the Bluetooth icon turns green and stops blinking.
The next stage involves the car icon blinking—this is the adapter setup and vehicle connection check. This stage is not covered in this guide.
Step 1. Ensure your ELM327 adapter supports classic Bluetooth connection (not Wi-Fi or Bluetooth LE).
Bluetooth LE adapters (versions 4.x or 5.x) use a different technology, though some models also support classic Bluetooth.
Step 2. Locate the OBD-II diagnostic port in your vehicle. Insert the adapter firmly until it is fully seated.
Step 3. Turn on the vehicle's ignition or start the engine. If the adapter has a power button, press it to turn it on. Verify that the adapter's LED indicator lights up.
Step 4. Search for and pair the adapter with your Android device.
Open Android system settings (not within the app) → Bluetooth section. Enable Bluetooth.
You'll see two lists: Connected devices and Available for pairing (they may be empty or long). Within a few seconds, the adapter should appear as OBDII or its brand name (e.g., VGate, Viecar, etc.).
If it doesn't appear, tap Search / Refresh to restart the scan.
💡 Important: You're connecting to the adapter, not the car! Do not select devices named after your car or infotainment system.
Step 5. Tap the found adapter. The system will likely request a PIN code.
Common codes are: 1234, 1111, 0000, or 7890. After successful pairing, the adapter will move to the connected devices list. Your Android device now "remembers" this adapter.
Step 6. Open Obd Mary app → Settings → Connection and confirm that Connection type is set to Bluetooth.
Step 7. Tap Bluetooth devices. Grant permission to scan for nearby devices, or tap the green hint at the top and enable it manually in system settings.
Return to Bluetooth devices — a list of Bluetooth devices will appear.
Select your adapter from the Paired devices list and tap OK in the top-right corner.
Step 8. Go to the main screen of the Obd Mary app and tap the blue Connect button at the bottom.
With a working adapter and correct steps, the app will connect. The Bluetooth indicator stops blinking, and the car icon starts blinking—this means the adapter is connected, and the app is configuring it for ECU communication.
For subsequent connections:
Insert adapter into diagnostic port → Turn on ignition → Open Obd Mary app and tap Connect.