Using a USB Car Code Scanner with Linux

A recurring car error code can be frustrating, especially when a trip to the garage doesn’t solve the issue. Thankfully, a USB car code scanner and Linux software offer a DIY solution. This guide explains how to use a USB OBD-II scanner with Linux, specifically using the scantool software. We’ll cover installation, usage, and provide helpful screenshots.

OBD-II Connector: Location and Types

Since 2004, all cars sold in the EU have been required to have a standardized On-Board Diagnostics (OBD) connector. Regulations mandated an easily accessible OBD-II connector within two feet of the steering wheel by 2007. These connectors come in USB and Bluetooth versions, ranging from inexpensive generic models to pricier, feature-rich options. A simple USB scanner is sufficient for reading and clearing basic error codes.

Installing Scantool on Linux

Scantool is a free software application available in the Ubuntu Universe repository, making installation straightforward. Open a terminal and execute the following commands:

sudo apt-get update
sudo apt-get install scantool

Scantool needs access to the OBD device, typically located at /dev/ttyUSB0. This device is owned by root and belongs to the dialout group. To use scantool without sudo, add your user to the dialout group:

sudo usermod -a -G dialout $USER

Important: Avoid running scantool with sudo. While it might work, it grants unnecessary privileges, violating the principle of least privilege. Adding your user to the dialout group provides sufficient access.

Using Scantool: Reading and Clearing Codes

After adding your user to the dialout group, log out and back in, or use the newgrp command to apply the changes immediately:

newgrp dialout

Verify your group membership with the groups command. “dialout” should appear in the list. With the car’s ignition turned on, connect the USB scanner and launch scantool:

scantool

The main menu will appear. Select “read codes” to retrieve error codes and their explanations. While codes are standardized, manufacturer-specific interpretations may exist, resulting in multiple explanations for a single code.

To clear a code, select the “clear” option after understanding its meaning and implications. Caution: Consult a mechanic if unsure about a code’s meaning. Clearing codes without understanding the underlying issue could mask a serious problem.

Return to the main menu and choose “sensor data” to view real-time sensor readings. The engine must be running for this feature to function correctly.

While the “tests” option might not be implemented in all builds, scantool provides ample functionality for diagnosing and resolving common car issues using a Usb Car Code Scanner Linux.