An old Android tablet can still be useful in the car, even if the vehicle does not have Android Auto built in.
Open Headunit is an open-source Android app that can turn an Android tablet, phone or compatible Android-based display into an Android Auto receiver. That allows a separate Android phone to project the familiar Android Auto interface onto the device for navigation, music, calls and other supported apps.
The project supports both wired and wireless connections, although the best setup depends on the Android versions involved, the tablet’s hardware and how permanently the device will be used in the car.
What You Need
For the display side, Open Headunit supports Android devices running Android 4.1 or later. A wired setup also requires the tablet or head unit to support the necessary USB connection, while wireless use requires Wi-Fi.
For wireless Android Auto, the project currently lists Android 10 or later on the phone as a prerequisite. Open Headunit’s documentation also recommends 5 GHz Wi-Fi where possible because 2.4 GHz connections are more likely to suffer from lag, stuttering or disconnects.
A secure mount and reliable power source are also worth planning before using a tablet as a permanent in-car display. The screen should not block the driver’s view or require unnecessary interaction while driving.
A Wired Connection Is the Simplest Place to Start
For many users, USB is the easiest way to determine whether a tablet and phone work properly with Open Headunit before spending time configuring wireless connections.
Install Open Headunit on the tablet or Android display and make sure Android Auto is available on the phone.
Connect the phone to the Open Headunit device using USB, open the app and choose the USB connection option. The Android device may display a permission prompt before the phone appears as an available connection.
Once selected, Android Auto should begin projecting to the second screen.
Starting with USB also removes Wi-Fi conditions from the equation, which can make troubleshooting easier if Android Auto does not initially start.
Wireless Android Auto Has Several Options
Wireless connections are more convenient, but Open Headunit currently provides several methods because not every device behaves the same way.
Its default Native Mode implements the wireless Android Auto connection directly and can use either Wi-Fi Direct or a hotspot created by the head unit. This avoids requiring a separate helper application on the phone.
Wi-Fi Direct is particularly useful for a dedicated in-car tablet because the phone and display can communicate directly instead of depending on another Wi-Fi network.
A hardware wireless Android Auto dongle is another option. Open Headunit’s developers describe this as the most reliable approach because the dongle handles the wireless negotiation independently.
There is also a developer-oriented Headunit Server method built into Android Auto, although it requires enabling Android Auto’s developer settings and manually starting the server on the phone.
Adjust the Display if Android Auto Does Not Fit Properly
Repurposed tablets and aftermarket Android displays come in many resolutions and aspect ratios, so Android Auto may not look correct with the default settings.
Open Headunit provides controls for resolution, pixel density, video decoding and screen scaling. The project’s documentation also includes hardware-specific settings and an optimization tool intended to help select suitable display and codec settings.
If Android Auto becomes stuck while starting, the project recommends checking the selected video codec. Some devices have problems decoding H.265 video, and switching to H.264 can resolve the issue.
Portrait-mode displays can present another problem. Open Headunit notes that touch input in Google Maps may behave incorrectly on some portrait devices and suggests trying a lower display density if that occurs.
Connection Drops Often Point to Wi-Fi Settings
If wireless Android Auto connects but regularly drops, the problem may not be Open Headunit itself.
The project recommends using 5 GHz Wi-Fi where possible. Phone features that automatically abandon Wi-Fi networks without internet access can also interfere with the connection because a direct connection to a head unit does not necessarily provide internet service.
Battery-saving settings can cause similar problems if Android shuts down a required background connection.
For persistent wireless issues, testing the same phone and tablet over USB can help determine whether the problem is related to Android Auto projection generally or only the wireless connection.
An Old Tablet Can Become a Dedicated Car Display
Open Headunit can be useful for vehicles with an older stereo, a basic dashboard screen or no Android Auto support at all.
It does require more setup than a factory Android Auto system, and compatibility can vary considerably between tablets, phones and aftermarket Android hardware. But starting with a wired connection, confirming video and audio behavior, and then adding wireless connectivity can make the setup easier to troubleshoot.
The project’s wiki includes current setup instructions, hardware guidance and troubleshooting information, which is particularly useful because Android Auto updates can change which connection methods work reliably.
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