OBDII

Overview

Connect to any vehicle through its OBDII port and start reading real-time data from Python in a few lines of code.

Plug in a USB, Bluetooth, WiFi or Ethernet adapter, then query engine speed, fault codes, fuel level, VIN, and much more.

Whether you’re building a diagnostic tool, a performance data logger, a custom dashboard, a smart home integration, or just learning how vehicles communicate, this library handles the complexity of vehicle communication, so you don’t have to.

Installation

Python 3.8 or higher is required.

Install from PyPI using pip:

pip install py-obdii

For more installation options, see the Installation Guide.

Usage Example

from obdii import Connection, at_commands, commands
from obdii.utils.scan import scan_ports

# Find first available OBDII device connected via serial
ports = scan_ports(return_first=True)
if not ports:
    raise ValueError("No OBDII devices found.")

# Connect to the adapter
with Connection(ports[0]) as conn:
    # Query adapter firmware version
    version = conn.query(at_commands.VERSION_ID)
    print(f"Version: {version.value}")

    # Query vehicle's engine speed (rpm)
    response = conn.query(commands.ENGINE_SPEED)
    print(f"Engine Speed: {response.value} {response.units}")

More examples in the examples folder and Usage Guide.

Emulator Support

You don’t need a physical OBDII device to start developing.

You can use the ELM327-Emulator library to simulate an OBDII adapter and vehicle responses.

Setting Up the ELM327-Emulator

Install the library with the sim extra options:
pip install py-obdii[sim]
Start the ELM327-Emulator:
python -m elm -p "REPLACE_WITH_PORT" -s car --baudrate 38400
Note

Replace REPLACE_WITH_PORT with the serial port of your choice

For platform-specific instructions, see the Emulating a Vehicle guide.

Hardware Requirements

For real-world usage, an ELM327-compatible OBDII adapter is required to connect to your vehicle.

USB: reliable, plug and play
Ethernet: reliable, low latency
Bluetooth: wireless, convenient
WiFi: wireless, mobile compatible

More information on connecting to different adapter types can be found in the Connection Guide.

Compatibility

All ELM327 protocols are supported, covering vehicles from the mid-1990s through today.

Protocol Support

ID	Protocol	Specifications
0x01	SAE J1850 PWM	41.6 Kbaud
0x02	SAE J1850 VPW	10.4 Kbaud
0x03	ISO 9141-2	5 baud init, 10.4 Kbaud
0x04	ISO 14230-4 KWP	5 baud init, 10.4 Kbaud
0x05	ISO 14230-4 KWP	fast init, 10.4 Kbaud
0x06	ISO 15765-4 CAN	11 bit ID, 500 Kbaud
0x07	ISO 15765-4 CAN	29 bit ID, 500 Kbaud
0x08	ISO 15765-4 CAN	11 bit ID, 250 Kbaud
0x09	ISO 15765-4 CAN	29 bit ID, 250 Kbaud
0x0A	SAE J1939 CAN	29 bit ID, 250 Kbaud
0x0B	USER1 CAN	11 bit ID, 125 Kbaud
0x0C	USER2 CAN	11 bit ID, 50 Kbaud

Support & Contact

Found a bug?

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