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Frequently Asked Questions (FAQ)

General Questions

What is CarOS Profile Switcher?

A Magisk module that automatically switches your Android device's settings based on whether you're using Android Auto (wired or wireless) or not in your car.

Do I need root access?

Yes, this module requires:

  • Rooted Android device
  • Magisk v20.4 or higher installed

Will this void my warranty?

Rooting your device and installing Magisk modules may void your warranty. Use at your own risk.

Does this work with all Android versions?

Tested on Android 10-14. Some features may not work on older/newer versions due to API changes.

Installation & Setup

Where do I download the module?

Download the latest ZIP from:

  1. The rel/ directory in this repository
  2. GitHub Releases page (recommended)
  3. Build it yourself using build.ps1 or build.sh

How do I install?

  1. Download the ZIP file
  2. Open Magisk Manager app
  3. Tap Modules tab
  4. Tap Install from storage
  5. Select the ZIP file
  6. Reboot when prompted

The module isn't working after installation

Check these:

  1. Magisk version is 20.4 or higher
  2. Android Auto app is installed
  3. You've paired your car via Bluetooth
  4. Module is enabled in Magisk Manager
  5. Check logs: adb shell cat /data/adb/modules/caros-switcher/log.txt

Where is the configuration file?

/sdcard/CarOS/config.env

The module creates this automatically on first boot. You can edit it with any text editor.

Do I need to reboot after changing config?

No! The configuration is reloaded automatically. Just connect to your car and the changes take effect.

Configuration Questions

How do I find my car's Bluetooth name?

Method 1 (easiest):

  1. Go to Settings > Bluetooth
  2. Look at paired devices
  3. Your car's name is listed there

Method 2 (using logs):

  1. Set VERBOSE=1 in config
  2. Connect to your car
  3. Check logs for Bluetooth device names

See EXAMPLES.md for more details.

My car's Bluetooth name keeps changing!

Some cars append numbers or change names. Use MAC address matching instead:

AUDI_BT_MAC="AA:BB:CC:DD:EE:FF"  # Your car's MAC address

Can I use this with multiple cars?

Yes! Use regex patterns:

AUDI_BT_NAMES="Audi|BMW|Rental"

What if my car name has special characters?

Escape them with backslashes:

AUDI_BT_NAMES="Car \\(2024\\)|John's Car"

Feature Questions

Does this work with wireless Android Auto?

Yes! It detects both wired (USB) and wireless (Bluetooth) Android Auto connections.

What is automatic permission management?

The module automatically grants necessary permissions to critical apps:

  • Notification permissions: Android Auto, Waze, Google Maps, Nova Launcher, Spotify
  • Location permissions: Google Maps, Waze, Android Auto (including background location)

This fixes the common issue where Android Auto requests permissions on every connection. Permissions are granted on boot and re-checked every 30 minutes.

Can I disable automatic permission management?

Yes, set AUTO_GRANT_PERMISSIONS=0 in your config file:

AUTO_GRANT_PERMISSIONS=0

Why does Android Auto keep asking for permissions?

If you have AUTO_GRANT_PERMISSIONS=0 or the module just installed, you may need to manually grant permissions once, or enable the automatic permission feature.

Why isn't WiFi turning off/on?

Some Android versions restrict WiFi control. Check:

  1. No battery optimization for system apps
  2. Check logs for error messages
  3. Try toggling KEEP_WIFI_IN_WIRED setting

Battery saver isn't enabling automatically

Some devices don't allow apps to enable battery saver. This is an Android restriction on newer versions.

Can I customize CPU throttling?

Yes! Set IDLE_MAX_CPU_FREQ in kHz:

IDLE_MAX_CPU_FREQ="1516800"  # ~1.5 GHz

Leave empty to disable CPU throttling.

What's the "charge limiting" feature?

In wired mode, the module tries to reduce fast charging to prevent phone overheating during long drives. This is "best effort" and may not work on all devices.

Does Nova Launcher need to be installed?

No. If SET_NOVA_DEFAULT=1 but Nova isn't installed, the module just skips this step. No errors.

How does audio streaming work?

CarOS supports two methods for streaming audio from another phone:

Method 1: Bluetooth A2DP Sink When ENABLE_BT_AUDIO_SINK=1, your CarOS phone becomes discoverable and can receive audio from another phone via Bluetooth.

Limitation: May not work if Bluetooth is already used for car audio/calls, even in wired mode.

Method 2: WiFi Hotspot (Recommended) When ENABLE_WIFI_AUDIO_HOTSPOT=1, your CarOS device creates a WiFi hotspot that other devices can connect to for streaming audio.

Advantages: Works even when Bluetooth is used by the car. Requires an audio streaming app on the emitting phone.

To use WiFi hotspot:

  1. Enable in config: ENABLE_WIFI_AUDIO_HOTSPOT=1
  2. Set SSID and password: WIFI_AUDIO_HOTSPOT_SSID="CarOS-Audio"
  3. Connect to car via USB (wired mode)
  4. Emitting phone connects to WiFi hotspot
  5. Use audio streaming app (SoundWire, AudioRelay, etc.)

Does Bluetooth audio sink work on all devices?

No, it's device-dependent. Some Android devices don't support A2DP sink mode. Additionally, even in wired mode, many cars use Bluetooth for audio and phone calls, which prevents the phone from acting as an A2DP sink simultaneously.

If Bluetooth doesn't work: Use the WiFi hotspot method instead (ENABLE_WIFI_AUDIO_HOTSPOT=1).

Why isn't my phone discoverable for Bluetooth audio?

If ENABLE_BT_AUDIO_SINK=1 but your phone isn't discoverable:

  1. Bluetooth may be in use by the car - Even in wired mode, many cars use Bluetooth for audio/calls
  2. Try WiFi hotspot instead - Set ENABLE_WIFI_AUDIO_HOTSPOT=1
  3. Check that you're in WIRED mode (USB connection)
  4. Look for "BT Audio Sink" messages in logs
  5. Your device may not support A2DP sink mode

Can I use audio streaming in IDLE mode?

No, both features are automatically disabled in IDLE mode to save battery. They only work when connected to your car in WIRED mode.

Can I use audio streaming in WIRELESS mode?

No, in wireless mode both Bluetooth and WiFi are typically used by the car for Android Auto connection. The audio streaming features only work in WIRED mode where the car connection is via USB.

What audio streaming apps work with WiFi hotspot?

Popular options include:

  • SoundWire (free) - Low latency audio streaming
  • AudioRelay (free) - WiFi/USB audio streaming
  • AirMusic - DLNA/UPnP streaming
  • Any app that supports streaming to a WiFi network

Troubleshooting

Module not detecting Android Auto

Check:

  1. Android Auto app is installed and running
  2. You're connected to your car (USB or Bluetooth)
  3. Enable VERBOSE=1 and check logs
  4. Verify process name: pidof com.google.android.projection.gearhead

Profiles not switching

  1. Check logs: adb shell cat /data/adb/modules/caros-switcher/log.txt
  2. Verify Bluetooth name matches: AUDI_BT_NAMES="Your Car Name"
  3. Try MAC address matching instead
  4. Ensure Android Auto is actually running (not just connected)

"Permission denied" errors in logs

Some features require specific permissions:

  • WiFi/Bluetooth control: Usually works
  • Battery saver: May be restricted on Android 12+
  • CPU frequency: Requires kernel support

These are best-effort features. Some may not work on all devices.

Logs show "dumpsys failed"

This usually means:

  1. Running on older Android version
  2. SELinux blocking access (rare with Magisk)
  3. System service isn't running

Try rebooting. If persists, the module will use fallback detection methods.

Battery draining faster

Check your configuration:

  1. DATA_OFF_OUTSIDE=1 (disable data when idle)
  2. KEEP_WIFI_IN_IDLE=0 (disable WiFi when idle)
  3. Set IDLE_MAX_CPU_FREQ to throttle CPU
  4. Ensure VERBOSE=0 (verbose logging uses more battery)

Phone getting hot in car

This is normal during Android Auto use. The module tries to help:

  1. LIMIT_QUICK_CHARGE_WIRED=1 reduces charging heat
  2. Ensure good phone ventilation in car
  3. Consider a phone mount with cooling

Advanced Questions

Can I edit the module scripts directly?

Yes, but changes will be lost on module updates. Better to:

  1. Fork the repository
  2. Make your changes
  3. Build your own version
  4. Consider contributing back via pull request

Where are the module files located?

/data/adb/modules/caros-switcher/     # Module directory
/data/adb/modules/caros-switcher/log.txt  # Logs
/data/adb/modules/caros-switcher/state.json  # Current state
/sdcard/CarOS/config.env               # User configuration

How do I uninstall?

  1. Open Magisk Manager
  2. Go to Modules
  3. Tap Remove on CarOS Profile Switcher
  4. Reboot

Configuration file at /sdcard/CarOS/ will remain (delete manually if desired).

Can I pause the module temporarily?

Yes:

  1. Open Magisk Manager
  2. Disable the module
  3. Reboot

Or keep enabled but set conservative settings.

How much battery does the module use?

Minimal. The service checks every 3 seconds, which uses negligible battery. Most battery usage comes from Android Auto itself, not this module.

What's the loop count in logs?

Service alive, loop #300

This appears every ~5 minutes (100 loops × 3 seconds) to prove the service is running. It's normal.

Compatibility

Does this work on LineageOS?

Yes! Tested and working. The module includes specific handling for LineageOS's delayed /sdcard mounting.

Does this work on Samsung devices?

Should work, but Samsung's One UI has aggressive battery optimization. You may need to:

  1. Disable battery optimization for system services
  2. Add Magisk to "Never sleeping apps"
  3. Disable "Adaptive battery"

Does this work on Pixel devices?

Yes, well-tested on Pixel devices.

Does this work with aftermarket head units?

Yes! As long as the head unit supports Android Auto (wired or wireless), this module will work. You just need to configure the Bluetooth name correctly.

Performance & Safety

Is this safe to use while driving?

Yes. The module:

  • Runs in background
  • Doesn't interrupt Android Auto
  • Automatically turns screen off (can be disabled)
  • Designed specifically for in-car use

Will this interfere with Android Auto?

No. The module monitors Android Auto but doesn't modify it. Profile switching happens in the background.

Can this cause bootloops?

Very unlikely. The module:

  • Uses standard Magisk framework
  • Doesn't modify system partitions
  • Can be disabled from Magisk recovery if needed

If issues occur, boot to recovery and disable/remove via Magisk.

Development & Contributing

How do I report bugs?

  1. Enable VERBOSE=1 in config
  2. Reproduce the issue
  3. Collect logs: adb shell cat /data/adb/modules/caros-switcher/log.txt
  4. Open a GitHub issue with logs and details

Can I contribute?

Absolutely! See CONTRIBUTING.md for guidelines.

How do I build from source?

# PowerShell
.\build.ps1

# Bash
./build.sh

What language is this written in?

Shell script (Bash/sh) - standard for Magisk modules.

Still have questions?

  1. Check EXAMPLES.md for configuration examples
  2. Check CONTRIBUTING.md for development info
  3. Open an issue on GitHub with your question
  4. Include logs and device info for technical questions

Remember: Always include logs when asking for help!

adb shell cat /data/adb/modules/caros-switcher/log.txt