CVTz50  |  CVT diagnostics with ELM327

• First, make sure the ELM327 adapter is working. Many adapters have LEDs that light up when power is present and blink while data is being exchanged with the app.
  In cold weather (below 5°C / 41°F), adapters may fail permanently or until warmed to room temperature.
  You can partially check the adapter by running the ELM327 Identifier test app.
• In CVTz50→Menu→Settings→Connection→Select Adapter Type, make sure the selected adapter type matches your ELM327 adapter: Bluetooth, BLE, Wi-Fi, or USB
• Only one diagnostic app can be connected to an ELM327 adapter at a time. Make sure no other app is connected to or attempting to connect to the adapter (including CVTz50 DEMO and ELM327 Identifier).
• Usually, only one external device can actively communicate with the vehicle’s ECUs at a time: an ELM327 adapter, CAN-connected alarm system, LPG controller, or third-party trip computer. If several devices attempt to work with the vehicle at once, they may interfere with each other.

Common ways to resolve Bluetooth connection problems:

• Bluetooth must be enabled on the Android device. In some cases the app can enable disabled Bluetooth automatically, but this is not permitted everywhere.
• On recent Android versions, grant all permissions requested when the app first starts, including location access. Your actual location is generally irrelevant, but Android treats Bluetooth device scanning as a way of determining proximity to Bluetooth beacons. If permissions were not granted initially, try enabling them through the list of installed apps in the device settings. This does not always work; you may need to uninstall and reinstall the app so that all permission prompts appear again. A sign of missing permissions is when the paired device list in CVTz50→Menu→Settings→Connection→Manually select/find is empty even though paired devices are visible in Android settings.
• If the adapter was used with one Android device, switching it to another Android device may require rebooting the adapter. When changing Android devices, first remove the adapter from the paired device list on the old Android device, then reboot the adapter — unplug it from the OBD-II connector for a few seconds and plug it in again — and only then pair it with the new device.
• If an ELM327 adapter supports both “classic Bluetooth 2.0/3.0” and “BLE/4.0” modes and appears as two Bluetooth devices with different names — typically one for BT 2.0/3.0 and the other for BLE/4.0 — select the appropriate name in CVTz50→Menu→Settings→Connection→Manually select/find. It must match the adapter type selected in CVTz50→Menu→Settings→Connection→Select Adapter Type
• Android Bluetooth may freeze, particularly after repeated unsuccessful pairing or connection attempts. Reboot the Android device.

Classic Bluetooth (not BLE/4.0)

• Before connecting, the ELM327 adapter must be paired with the Android device through Android settings.
• If connection problems occur, remove all paired ELM327 adapters — or, as a more radical and reliable option, remove all paired Bluetooth devices — and pair the adapter again. If you need to keep several ELM327 adapters paired, select the preferred adapter in CVTz50→Menu→Settings→Connection→Manually select/find

Bluetooth Low Ennergy (BLE/4.0)

• BLE/4.0 adapters normally do not need to be paired in advance through Android settings. However, you must select such an adapter through CVTz50→Menu→Settings→Connection→Manually select/find→Find devices

Bluetooth stability

If the connection is established but unstable, disconnects frequently, monitoring intermittently reports dropped frames, or some functions do not always open:

• Place the Android device closer to the ELM327 adapter and eliminate interference from other Wi-Fi, Bluetooth, or similar wireless devices.
• If the adapter was paired with other Android devices, remove it from the paired device lists on those devices.
• If both the adapter and Android device support classic Bluetooth and BLE/4.0, try both modes; one may work better.
• Many Android devices cannot work reliably with several Bluetooth devices simultaneously — for example, a wireless headset during a call and ELM327 diagnostics. If the ELM327 adapter and headset use different Bluetooth versions, the probability of conflicts increases significantly.
• Some Android devices, especially 3rd party head units, have poor Bluetooth drivers. In many cases, updated firmware or other solutions may improve the connection. If no solution works, switch to a Wi-Fi adapter.
• A defective Bluetooth module in the adapter may cause disconnects.
• If the connection always drops at the same point during connection or vehicle control modules detection, this may indicate a generally low-quality adapter (https://cvtz50.info/elm327/) or a defective Bluetooth module.

Make sure that the IP address and port configured in CVTz50→Menu→Settings→Connection match the IP address and port specified in the ELM327 adapter’s documentation. CVTz50’s default values work for most adapters, but exceptions exist.

Wi-Fi adapter connection issues are usually related to two Android Wi-Fi behaviors:

• When connected via Wi-Fi, Android expects that Wi-Fi network to provide Internet access. If it detects that the ELM327 Wi-Fi network has no Internet access, it may disconnect from it.
  To prevent this, enable Android Wi-Fi setting similar to: "Do not disconnect from Wi-Fi even if it does not provide Internet access"
• Android may incorrectly route the app’s attempt to connect to ELM327 through mobile data rather than the Wi-Fi connection.
  To confirm this is the cause, temporarily disable mobile data and try connecting to ELM327 again; the app should connect.
  To use a Wi-Fi ELM327 adapter while mobile data remains enabled, turn on CVTz50→Menu→Settings→Connection→Bind Connection to Wi-Fi Network,then test “Method 1” and “Method 2” to determine which works with your Android device.

Make sure the Android device supports USB Host mode.

The app supports common USB interfaces including FTDI, Prolific, CH340, and CP210x. Some adapters may use other USB chips; in that case, the app will not detect the USB ELM327 adapter. Contact info@cvtz50.info and provide the adapter’s VendorId and ProductId.