Encountering issues connecting your OBD II Bluetooth scanner to your device can be frustrating. This guide, created by the experts at obd2scanner.store, will walk you through common problems and their solutions, ensuring you can get back to diagnosing your vehicle quickly. This article focuses specifically on connection problems between your OBD II scanner and your Bluetooth device (like your smartphone or tablet), not issues connecting to your vehicle’s ECU.
Issue #1: Incorrect Device Selection in App Settings
One of the most frequent causes of connection failure is simply selecting the wrong Bluetooth device within your car scanning app’s settings. Users sometimes mistakenly choose other Bluetooth devices, such as car multimedia systems or headphones, instead of their OBD II adapter.
Solution: Navigate to the settings menu within your OBD app. Look for sections labeled “Adapter,” “Connection,” or “Bluetooth.” Within this area, there should be a “Device Name” or “Select Device” field. Tap this field to view a list of available Bluetooth devices. From this list, select your ELM327 adapter.
Key identifiers for your OBD II adapter’s name:
- Often includes “OBDII” or “OBD 2”
- May contain the brand name of the adapter (e.g., Viecar, V-Link, OBDLink)
- Crucially, it will NOT be the brand of your car or phone. Avoid selecting options like “MyCar,” “Toyota,” “Android,” or “iPhone.”
Issue #2: Multiple Adapters with the Same Name
It’s possible to have multiple Bluetooth devices with identical names (often just “OBDII”). While the name might be the same, each device has a unique Bluetooth address. Connection is established via this address, not the name. Therefore, if you have multiple OBD II adapters and select the wrong one in your app, communication will fail.
Solution: Return to your app’s Bluetooth device selection settings as described in Issue #1. Carefully review the list of available devices. If you see multiple entries with the same name (e.g., “OBDII”), try each one in turn until you establish a connection.
To prevent future confusion: Consider “forgetting” or removing unused Bluetooth devices from your phone’s Bluetooth settings. This will minimize the list of devices you need to sort through in your OBD app.
Issue #3: Incompatible Connection Type (Bluetooth vs. Bluetooth LE)
Bluetooth technology has evolved, and there are two primary types relevant to OBD II scanners: “Classic” Bluetooth and Bluetooth Low Energy (LE) or Bluetooth 4.0. These are fundamentally different communication methods.
- Classic Bluetooth: The more traditional and widely compatible type. Most ELM327 adapters use classic Bluetooth.
- Bluetooth LE (4.0): A newer, energy-efficient standard. Some newer OBD II adapters, like Kiwi 3 and OBDLink CX, utilize Bluetooth LE.
Compatibility is key:
- If your adapter is classic Bluetooth only, you must select the “Bluetooth” or “Classic Bluetooth” connection method in your app.
- If your adapter is Bluetooth LE only, you must select the “Bluetooth LE” or “Bluetooth 4.0” connection method.
- Some advanced adapters, like OBDLink MX+, support both. On Android, classic Bluetooth is generally recommended for these dual-mode adapters. iOS devices, however, typically require Bluetooth LE for OBD II connections (with exceptions like the OBDLink MX+ which has special Apple certification).
Solution: Check your OBD adapter’s specifications to determine whether it uses classic Bluetooth or Bluetooth LE. Then, ensure you have selected the corresponding connection type in your car scanner app’s settings. Incorrectly choosing Bluetooth LE for a classic Bluetooth adapter (or vice-versa) will prevent communication.
Important Note: The Bluetooth version of your phone (e.g., Bluetooth 5.0) is not the issue. Compatibility hinges on the type of Bluetooth (Classic or LE) supported by your adapter and selected in your app. Don’t assume Bluetooth LE is inherently “faster” for OBD II applications.
Issue #4: Another App is Blocking the Connection
Only one app can communicate with your Bluetooth OBD II adapter at a time. If another car scanning app (or any app that might be trying to access Bluetooth) is running in the background or foreground, it could be holding the connection and preventing your current app from connecting.
Solution: Completely close any other OBD II apps or apps that might be using Bluetooth.
- iOS: Use the task switcher to force quit all other OBD apps.
- Android: Force closing apps via the task switcher may not be sufficient. Some apps may run background services that maintain a Bluetooth connection. Check within the app’s settings for a “disconnect” or “exit” option to fully release the Bluetooth connection. You can also try force stopping the app in Android settings (Settings -> Apps -> [App Name] -> Force Stop).
Issue #5: Adapter Freeze, Hang, or Power Off
Like any electronic device, your OBD II Bluetooth adapter can sometimes freeze, become unresponsive, or simply power off unexpectedly.
Solution:
- Power Cycle: The simplest solution is to physically disconnect the adapter from your vehicle’s OBD II port and then reconnect it. This often resets the adapter.
- Check Power Button (if applicable): Some adapters have a power button. Ensure the adapter is turned on. If it is on, try turning it off and then back on again.
Issue #6: Phone/Tablet Bluetooth Stack Glitches
Your phone or tablet’s Bluetooth system (the software and drivers that manage Bluetooth) can sometimes experience temporary glitches or freezes. This can prevent new Bluetooth connections.
Solution:
- Toggle Bluetooth: Turn Bluetooth off and then back on again in your phone’s settings. This often resolves minor Bluetooth stack issues.
- Restart Your Device: If toggling Bluetooth doesn’t work, restart your phone or tablet completely. This refreshes the entire operating system and Bluetooth stack, often clearing up more persistent glitches.
Issue #7: Insufficient Bluetooth Permissions
Your car scanning app needs permission to access your device’s Bluetooth functionality. If these permissions are not granted, the app will be unable to communicate with your OBD II adapter.
Solution: Check and grant Bluetooth permissions to your car scanner app in your phone’s settings. The exact steps vary slightly depending on your operating system version:
- Android 6.0 – 11 (and some 12): Go to Android Settings -> Apps -> [Your Car Scanner App] -> Permissions. Look for “Location” or “Geolocation” permissions and ensure they are enabled. (Note: Older Android versions sometimes incorrectly require location permissions for Bluetooth scanning).
- Android 12 and above: Go to Android Settings -> Apps -> [Your Car Scanner App] -> Permissions -> “Nearby devices”. Ensure “Nearby devices access” is allowed for the app.
- iOS: Go to iOS Settings -> Privacy & Security -> Bluetooth. Find your car scanner app in the list and ensure Bluetooth access is enabled for it.
Issue #8: Bluetooth Disabled or Adapter Power Off
This might seem obvious, but it’s easily overlooked. If Bluetooth is disabled on your phone or the OBD II adapter itself is not powered on, a connection is impossible.
Solution:
- Enable Bluetooth on your phone: Ensure Bluetooth is turned on in your phone’s settings or control panel.
- Check Adapter Power: If your adapter has a power button, make sure it is switched to the “on” position. Some adapters power on automatically when plugged into the OBD II port, while others require manual activation.
Issue #9 (Android Specific): Missing Bluetooth Access (System Glitch)
On Android, there’s a deeper level of Bluetooth permission that is usually granted automatically by the operating system when an app is installed. However, in rare cases, a system glitch during app installation can prevent this permission from being correctly assigned. This hidden permission issue won’t be visible in the standard app permissions settings.
Solution: Reinstall the car scanner app. Uninstalling and then reinstalling the app forces the Android operating system to re-grant all necessary permissions, including this underlying Bluetooth access permission, resolving the glitch.
Issue #10: The Adapter is Faulty (Dead Adapter)
Unfortunately, OBD II Bluetooth adapters, especially inexpensive ones, can fail. Adapter failure is more common than many users realize. If you’ve tried all the troubleshooting steps above and still cannot connect, a defective adapter is a strong possibility.
Solution: If none of the above steps resolve the connection issue, consider testing with a different OBD II adapter if possible. If a different adapter connects successfully, your original adapter is likely faulty and needs to be replaced. Purchasing a new, reliable OBD II adapter is the most practical solution in this case.
BONUS: App “Cannot See” the Adapter at All
If your car scanner app doesn’t even detect or list your adapter during the device selection process, this indicates a more fundamental discovery problem. This is often related to the issues already discussed:
Possible Reasons & Solutions (Review Solutions from Previous Issues):
- Wrong Connection Type Selected (Issue #3): Double-check that you’ve selected the correct Bluetooth type (Classic or LE) in your app’s settings, matching your adapter’s capabilities.
- Adapter Busy with Another App (Issue #4): Ensure no other apps are currently connected to or attempting to use the Bluetooth adapter.
- Insufficient Permissions (Issue #7): Review and grant all necessary Bluetooth and location/nearby devices permissions to your car scanner app.
- Adapter Freeze (Issue #5): Try power cycling the adapter by disconnecting and reconnecting it.
- Phone Bluetooth Glitch (Issue #6): Toggle Bluetooth off/on and restart your phone.
- Faulty Adapter (Issue #10): Consider the possibility of a dead adapter and test with a different one if available.
- Android Geolocation Requirement (Android 6+): On Android 6.0 and later, location services (geolocation) must be enabled for Bluetooth scanning to discover new Bluetooth LE devices. Ensure location services are turned on in your Android device’s settings, even if your adapter is classic Bluetooth (this is an Android system requirement for Bluetooth LE discovery, which can sometimes affect even classic Bluetooth scanning).
By systematically working through these troubleshooting steps, you should be able to identify and resolve the reason why your OBD II Bluetooth scanner is failing to communicate with your Bluetooth device and get back to diagnosing your vehicle.
