Windows Issues

Each section below opens with the exact message pcu shows on Windows, followed by how to clear it. For a clean install walkthrough see Install on Windows, and for driver management see the GUI Driver Page.

”Administrator privileges required”

The GUI splash screen stops with an error panel:

Administrator privileges required

pcu needs admin access to communicate with vehicle PC hardware.

Right-click pcu.exe and select 'Run as administrator'.

Run a hardware command from a terminal without elevation and pcu-cli prints the terse form:

ERROR: This program must be run as Administrator.
Hardware access requires elevated privileges (PawnIO kernel driver).

Double-clicking pcu-cli.exe without elevation shows the same error after the banner, then Press any key to exit....

pcu reaches the MCU through the PawnIO kernel driver, which only an elevated process can open. pcu.exe normally self-elevates and you approve a UAC prompt at launch; this message means that prompt was declined or elevation was blocked.

1. Close pcu.
2. Right-click pcu.exe (or pcu-cli.exe) and choose Run as administrator, or launch from an already-elevated Command Prompt or PowerShell.
3. Approve the UAC prompt.

help, version, and driver run unelevated; every command that touches hardware (status, ign, dio) needs elevation.

”PawnIO driver is not installed.”

The GUI fails to connect and the sidebar shows a connection error with a Driver Setup button; the Home page offers to install the driver. From a terminal, running a hardware command prompts:

PawnIO driver is not installed.
Install now from embedded resource? [y/N]

Answering anything but y:

Aborted. Install manually: winget install namazso.PawnIO

PawnIO is the kernel driver pcu uses for hardware access. The installer is bundled inside pcu, so you do not download anything separately.

1. In the GUI, open the Driver page and click Install, or on the Home page use the install prompt. Approve the UAC prompt.
2. Or from an elevated terminal: pcu-cli driver install.
3. Or install it yourself: winget install namazso.PawnIO.
4. If the install reports that a reboot is required, reboot before using pcu.

”Installation cancelled. UAC prompt was declined.”

Both the GUI Driver page and pcu-cli driver install show this when the driver installer’s UAC prompt is dismissed:

Installation cancelled. UAC prompt was declined.

The driver installer elevates separately from the app. Retry the install and click Yes on the UAC prompt. If your account cannot elevate, install as an administrator, or run winget install namazso.PawnIO from an elevated terminal.

”PawnIO driver installed. Reboot to complete installation.”

A successful install or removal can defer completion to the next reboot:

PawnIO driver installed. Reboot to complete installation.

Uninstalling always needs a reboot, because the kernel driver stays loaded until then:

PawnIO driver uninstalled. Reboot to complete removal.

Reboot Windows, then relaunch pcu or re-run pcu-cli status. Until you reboot, the driver status may not reflect the change.

”Installation failed. Try installing manually: winget install namazso.PawnIO”

The bundled installer could not complete:

Installation failed. Try installing manually: winget install namazso.PawnIO

1. Open an elevated terminal (Run as administrator).
2. Run winget install namazso.PawnIO.
3. Reboot if prompted, then relaunch pcu.

A removal that fails shows Uninstall failed. Try removing manually from Device Manager. instead; in that case remove the PawnIO device from Device Manager and reboot.

”pcu is already running.”

pcu allows a single instance. Launching a second copy shows a message box titled “pcu”:

pcu is already running.

Switch to the window that is already open. If no pcu window is visible, a previous instance may be stuck: end any pcu.exe process in Task Manager, then start pcu again. (The pcu-cli binary is not affected by this limit; only the GUI enforces a single instance.)

“pcu encountered a fatal error and must close.”

On an unexpected failure the GUI shows a message box titled “pcu - Fatal Error”:

pcu encountered a fatal error and must close.

<ExceptionType>: <message>

A crash log has been written to:
C:\Users\<you>\AppData\Local\pcu\crash.log

The log is appended (not overwritten) at %LOCALAPPDATA%\pcu\crash.log. pcu keeps no other runtime log.

1. Open %LOCALAPPDATA%\pcu\crash.log (paste that path into the Explorer address bar).
2. Copy the most recent entry, which is dated at the top.
3. Include it when you report the problem to In-CarPC support, along with your vehicle PC model.