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This page covers common issues you may encounter with BlueBus and their solutions.

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Bluetooth connectivity issues

Symptoms:
  • BlueBus not discoverable
  • Pairing fails repeatedly
  • Device connects but immediately disconnects
Solutions:
  1. Clear paired devices list
    • Navigate to Settings > Bluetooth > Clear Pairing List
    • This removes corrupted pairing records
  2. Reset Bluetooth module
    • Power cycle the vehicle (ignition off for 30 seconds)
    • BlueBus will automatically attempt to reconnect to the last device
  3. Check BC127 boot failure counter
    • If the BC127 Bluetooth module fails to boot multiple times, it may enter a protection mode
    • The failure counter is stored in EEPROM at CONFIG_INFO_BC127_BOOT_FAIL_COUNTER
    • A reset or firmware update may be required if failures exceed threshold
Some phones have compatibility issues with specific Bluetooth profiles. Try connecting with a different device to isolate the issue.
Symptoms:
  • Audio works but no track information displays
  • Phone calls don’t work but audio streaming does
  • Playback controls unresponsive
What happens internally: When BlueBus detects an OPEN_ERROR event for a specific profile, it:
  • Sets a pairing error flag for that profile (bt->pairingErrors[profile_index])
  • Automatically retries the connection after a timeout
  • If A2DP fails during initial connection, assumes complete connection failure
Solutions:
  1. Wait for automatic retry
    • BlueBus automatically retries failed profile connections every few seconds
    • You’ll see “Handler: Resolve pairing error” in debug logs when this occurs
  2. Manual profile reconnection
    • Disconnect and reconnect your device from vehicle Bluetooth settings
    • This triggers a fresh connection attempt for all profiles
  3. Check phone Bluetooth settings
    • Ensure all Bluetooth profiles are enabled on your phone
    • Some phones disable profiles like MAP or PBAP by default
Cause: AVRCP profile connection issueSolution:
  • AVRCP (Audio/Video Remote Control Profile) must be connected for metadata
  • Check debug logs for AVRCP connection status
  • Try toggling playback (pause/play) to trigger AVRCP activation
  • Some music apps don’t properly expose metadata via AVRCP
BlueBus polls for metadata every few seconds when audio is playing. If you see “BT: AVRCP Status” in logs but no metadata, the issue is likely with the source device or app.

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I-Bus communication problems

Log message:
[timestamp] ERROR: IBus: RX Invalid Length [length - 0xXX]: XX XX XX ...
Cause:
  • Corrupted I-Bus packet received
  • Electrical interference on I-Bus
  • Faulty I-Bus wiring or connection
What BlueBus does:
  • Resets the receive buffer
  • Clears the UART receive queue
  • Continues operation (does not crash)
Solutions:
  1. Check I-Bus wiring connections
  2. Ensure proper grounding
  3. Verify TH3122 I-Bus transceiver is functioning correctly
  4. If errors are frequent, inspect vehicle I-Bus for faults
Occasional invalid length errors are normal on older vehicles with electrical noise. Frequent errors (>10 per minute) indicate a wiring problem.
Cause:
  • I-Bus message started but never completed
  • Packet transmission interrupted
Impact:
  • Minimal - BlueBus discards the incomplete packet and continues
  • Buffer is cleared automatically after 100ms timeout
Solutions:
  • Usually resolves on its own
  • If persistent, check I-Bus voltage levels
  • Verify ignition power is stable
Cause:
  • BlueBus trying to send I-Bus messages faster than bus can handle
  • Transmit buffer full (16 message maximum)
Solutions:
  • This is rare and typically indicates a firmware issue
  • Update to latest firmware
  • Report to developer with debug logs if persistent

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Display and UI issues

Possible causes:
  1. Navigation system not detected
    • BlueBus auto-detects GT (Graphics Terminal) version on startup
    • If detection fails (IBUS_GT_DETECT_ERROR), UI may not display
    • Check debug logs for “GT Version” detection messages
  2. Wrong UI mode
    • Navigate to Settings > UI > Display Mode
    • Ensure correct display type is selected (BMBT/MID/CD53)
  3. I-Bus communication issue
    • Verify BlueBus is receiving I-Bus messages
    • Check for I-Bus errors in logs
You can test I-Bus communication by checking if the telephone LED responds (red = disconnected, green = connected).
Solutions:
  • Check Settings > UI > Language setting
  • Some characters may not display correctly on older displays
  • Try reducing metadata length in problematic apps
  • Update to latest firmware for character encoding fixes

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Audio quality issues

Check these in order:
  1. DAC power status
    • PCM5122 DAC must power on successfully
    • Check logs for “PCM51XX failed to power up” errors
  2. DSP input source
    • Navigate to Settings > Audio > DSP Input
    • Verify correct input is selected (analog or S/PDIF)
  3. Volume levels
    • Check both BlueBus volume and vehicle volume
    • Some vehicles have separate audio source volumes
  4. Wiring
    • Verify audio output connections
    • Check for shorts or open circuits
Log messages:
ERROR: WM88XX failed to set PLLCLK [status]
ERROR: WM88XX failed to power on [status]
Cause: I2C communication failure with audio codecSolutions:
  1. Check I2C bus connections (SDA/SCL lines)
  2. Verify I2C pull-up resistors are present
  3. Check for I2C address conflicts
  4. Power cycle to retry initialization
Persistent codec errors indicate a hardware problem. Contact support if errors continue after power cycle.
Solutions:
  • Adjust Settings > Audio > DAC Gain
  • Check ground connections
  • Verify power supply voltage is stable (11-14V)
  • Try different audio codec (AAC vs SBC)
  • Check for electromagnetic interference from vehicle electrical system

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Hands-free calling issues

Symptoms:
  • Caller can’t hear you
  • Poor voice quality
  • Voice recognition not working
Solutions:
  1. Adjust microphone gain
    • Settings > Telephony > Microphone Gain
    • Range: -27 dB to +39 dB (factory microphones typically need +15 to +30 dB)
  2. Check HFP connection
    • Verify HFP profile is connected
    • Look for “OPEN_OK HFP” in debug logs
  3. Test microphone wiring
    • Verify microphone is connected to correct input
    • Check for shorts or damage to microphone cable
BMW factory microphones are low-sensitivity and require gain adjustment. Start with +24 dB and adjust based on call quality.
Cause: SCO (Synchronous Connection-Oriented) link not establishedCheck logs for:
  • “BT: SCO Connected” (should appear when call starts)
  • “BT: SCO Disconnected” (should appear when call ends)
Solutions:
  • Ensure HFP profile is properly connected
  • Restart Bluetooth module (power cycle vehicle)
  • Update firmware if issue persists

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Firmware update issues

Symptoms:
  • Update starts but doesn’t complete
  • Device becomes unresponsive during update
  • Error messages in firmware tool
Solutions:
  1. Verify bootloader mode
    • Device must be in bootloader mode before update
    • Look for platform response from bootloader
  2. Check USB connection
    • Use a high-quality USB cable
    • Avoid USB hubs
    • Try different USB port
  3. Power requirements
    • Ensure vehicle battery is charged (>12V)
    • Don’t update with engine off on weak battery
  4. Flash erase issues
    • If erase phase fails, retry update
    • Bootloader will recover from incomplete flash
Never disconnect power during firmware update. The bootloader protects against bricking, but interruption will require restarting the update process.
Cause:
  • Firmware update interrupted
  • Corrupted application firmware
  • Bootloader mode flag set incorrectly
Solutions:
  1. Complete firmware update using firmware tool
  2. If update fails repeatedly, try different firmware version
  3. Check debug logs for flash write errors
  4. Contact support if issue persists after multiple update attempts

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Power and reset issues

Check:
  1. Ignition power (pin 30F on I-Bus connector)
  2. Ground connection
  3. Fuses
  4. I-Bus voltage (should be ~12V)
Voltage requirements:
  • Operating range: 9-16V DC
  • Typical: 12-14V
Possible causes:
  • Insufficient power supply
  • Short circuit
  • Thermal issues
  • Firmware crash
Diagnosis:
  1. Check debug logs for reset reason
  2. Monitor power supply voltage
  3. Check for thermal throttling
  4. Review logs before each reset for crash indicators
The BC127 module tracks boot failures. Excessive failures may indicate hardware problem. Check ConfigGetBC127BootFailures() in logs.

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Configuration issues

Cause: EEPROM write failureSolutions:
  1. Verify settings are saved (should see confirmation)
  2. Check for EEPROM errors in debug logs
  3. If persistent, EEPROM may be damaged - contact support
Settings are stored in EEPROM and should persist indefinitely. If they don’t, this indicates a hardware issue.
How to perform proper factory reset:
  1. Navigate to Settings > System > Factory Reset
  2. Confirm reset
  3. BlueBus will restart with default settings
  4. Re-pair your Bluetooth devices
If reset fails:
  • Power cycle vehicle
  • Try reset again
  • Check debug logs for EEPROM write errors

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Getting more help

If you’re still experiencing issues after trying these solutions:
  1. Capture debug logs
    • Connect to BlueBus via USB
    • Use a serial terminal at 115200 baud
    • Enable debug logging for relevant systems
    • Reproduce the issue while logging
  2. Use the log parser
  3. Check firmware version
    • Ensure you’re running the latest firmware
    • Check release notes for known issues
  4. Community support
    • Search existing issues on GitHub
    • Post on BlueBus forums with logs and details
  5. Contact developer
    • Provide debug logs
    • Include hardware version and firmware version
    • Describe vehicle make/model/year

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