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BMW INPA OBD2 USB 5.0.1 Download and Setup Guide for DIY Diagnostics

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For BMW enthusiasts and owners looking to delve into DIY diagnostics and coding, the combination of BMW INPA software, an OBD2 USB cable, and version 5.0.1 offers a powerful and cost-effective solution. This guide will walk you through understanding the necessary hardware, software, and step-by-step instructions to get your BMW communicating with your computer for in-depth analysis.

Understanding the Basics: KKL Protocol and BMW Diagnostics

Older BMW models utilize a communication protocol known as KKL (K-Line). Unlike modern CAN bus systems, KKL is a serial communication method operating at a 10.4kbaud data rate. This is important to understand because standard RS232 ports on computers are not directly compatible with KKL in terms of baud rate and signal levels. Direct connection could potentially damage your computer.

To bridge this gap, a USB OBD2 adapter is essential. This adapter converts the KKL protocol to USB, allowing your computer to interface with your BMW’s diagnostic system.

Connector Types: 16-Pin OBDII and 20-Pin Round Connector

BMWs from the late 90s and early 2000s often feature both a 16-pin OBDII connector and a 20-pin round connector located in the engine bay.

  • 16-Pin OBDII Connector: Primarily used for engine and gearbox diagnostics. The relevant pins for KKL communication are typically:

    • Pin 4 & 5: Ground (GND)
    • Pin 7: K-line (Engine & Gearbox – D_TXD2)
    • Pin 8: K-line (Other Modules – D_TXD1) – May not be populated on all models
    • Pin 16: 12V Power

  • 20-Pin Round Connector: Provides access to a wider range of modules, including ABS, Airbag, and other systems. Key pins include:

    • Pin 1: Engine rotation speed
    • Pin 2: OBD2 Diagnostic
    • Pin 7: Oil service and inspection reset
    • Pin 14: 12V Power
    • Pin 15: L-Line (Wake-up line, often not needed with ignition on)
    • Pin 17: K-line (2) (D_TXD2)
    • Pin 20: K-line (1) (D_TXD1)
    • Pin 19: Ground (GND)

For comprehensive diagnostics covering all modules, utilizing the 20-pin connector is generally recommended. However, for basic engine and gearbox checks, the 16-pin OBDII port can suffice.

Bridging the K-Lines for OBD2 Adapters

Many affordable OBD2 KKL USB adapters are designed to work with a single K-line on the OBD2 port (pin 7). To enable communication with all modules via the 20-pin connector, the two K-lines (pins 17 and 20 on the 20-pin connector) need to be bridged together and connected to pin 7 of the OBD2 adapter. BMW to OBD2 adapter cables are readily available and typically handle this bridging internally.

A common BMW 20-pin to OBD2 adapter, showing the OBD2 connector end.

Essential Hardware and Software

To get started with BMW INPA diagnostics, you’ll need the following:

  1. OBD2 KKL USB Adapter: Crucially, choose an adapter based on an FTDI or Prolific chipset. These chipsets are known for their compatibility and reliable performance with diagnostic software. Avoid CAN bus-only adapters, as they are not suitable for older KKL-based BMWs. Look for adapters explicitly advertised as “KL” or “KKL.” Pin 7 should be populated on the 16-pin OBD2 connector of the adapter.

  2. BMW 20-Pin to OBD2 Adapter Cable (Optional but Recommended): If you want to access all modules beyond just the engine and gearbox, this adapter cable is necessary for BMWs with a 20-pin diagnostic port. It simplifies the connection and internally bridges the K-lines.

  3. Laptop with Windows: INPA and related software are designed for Windows operating systems.

  4. BMW INPA Software Package (Version 5.0.1): This software suite is the core of your diagnostic setup. It typically includes:

    • EDIABAS (Electronic Diagnostic Basic System): The communication interface layer that handles the data exchange between your computer and the BMW.
    • INPA (Interface for Programmable Automotives): The main diagnostic software, providing a user interface to read fault codes, access live data, perform service resets, and more.
    • NCS Expert (NCS Expert Tool): Used for coding and programming modules, allowing for customization of vehicle settings.

INPA 5.0.1 Software Installation and Configuration Guide

Disclaimer: Modifying your vehicle’s software and settings carries risks. Proceed with caution and at your own risk. Always back up your system before making changes.

  1. System Restore Point and Registry Backup: Before starting any software installation, create a system restore point in Windows and back up your Windows Registry. This allows you to revert your system to a previous state if any issues arise during installation.

  2. Download INPA 5.0.1 Software: Search online for “INPA.iso download.” Exercise caution when downloading software from the internet and ensure you obtain it from a reputable source to avoid malware. Please note that providing direct download links to copyrighted software is not permissible.

  3. Extract the ISO File: Once downloaded, use software like WinRAR or 7-Zip to extract the contents of the INPA.iso file to a folder on your C: drive, for example, C:INPA_CD.

  4. Run the Installer: Navigate to the extracted folder: C:INPA_CDProgramminstallation. Run the setup.exe file.

  5. Installation Options: Follow the on-screen prompts. During the installation process, ensure you select:

    • Installation of INPA, EDIABAS, and NCS Expert (at a minimum for full diagnostic capability).
    • Full Installation (default is usually recommended).
    • OBD interface type.
    • USB to Serial for adapter connection.
    • Keep the option to add desktop icons ticked for easy access.

  6. Latency Timer Configuration: After installation, go to C:EDIABASHardwareOBD. Open the USB-OBD.pdf document. Follow the instructions in this PDF to adjust the latency timer of your USB to serial adapter from the default 16ms to 1ms. This is crucial for reliable communication. You will typically need to access your Device Manager, locate your USB Serial Port (often under Ports (COM & LPT)), go to Properties -> Port Settings -> Advanced, and change the Latency Timer value. Force the USB/serial adapter to COM1 in the same Advanced settings.

  7. Run OBDSetup.exe: Execute OBDSetup.exe located in C:EDIABASBIN. Do not close the command prompt window immediately. If you see a “Warning, some values do not match, malfunction can occur” message, it indicates registry discrepancies. You will need to manually edit the registry (using regedit) to correct these values. The warnings usually relate to DWORD values for buffer sizes and FIFO (First-In, First-Out) settings. Consult online resources or INPA documentation for specific registry keys and values. Run OBDSetup.exe again after registry edits to verify all warnings are gone. Reboot your computer if you make registry changes.

  8. Environment Variable: Add the following environment variable to your system: C:EDIABASBIN. This ensures that the system can find the necessary EDIABAS files. You can do this by searching for “environment variables” in the Windows search bar, clicking “Edit the system environment variables,” then “Environment Variables,” and editing the “Path” variable under “System variables.” Add ;C:EDIABASBIN to the end of the existing path.

  9. OBD.ini Configuration:

    • Open the file OBD.ini from C:EDIABASBIN.
    • Ensure the following lines are present and correctly configured under the [OBD] section:
    [OBD]
Port=Com1
Hardware=USB
RETRY=ON
UBAT=OFF
    • Copy the OBD.ini file from C:EDIABASBIN to C:Windows.

  10. Install INPA Guts: Navigate to C:INPA_CDReferenzINSTALL and run Installprog.exe. Choose “English” language and install “BMW Group Rectification programs UK.” Select “Upgrade” or preferably “Complete” installation when prompted. Complete the installation process.

Launching INPA and Testing Connection

After completing the installation steps, you should now be able to run INPA from the desktop icon. Upon launching, you should see both INPA and EDIABAS initializing. At the bottom of the INPA interface, you will typically find options to select your BMW model series and access various modules.

Troubleshooting Common Issues:

  • EDIABAS Initializing Errors: Re-check the registry DWORD values from step 7 and verify the USB/Serial latency timer configuration in step 6.
  • INPA IFH-0018 INITIALIZATION ERROR: This often indicates a COM port issue. Double-check that your USB adapter is correctly assigned to COM1 and configured in OBD.ini.
  • Communication Problems: If you are still having trouble connecting, download the INPA_FAQ document (search online for “INPA_FAQ forum b-m-w.ru”) for detailed error code explanations and troubleshooting tips. You can also use a terminal program like Tera Term to test communication on COM1 at 9600 baud to verify basic connectivity with your adapter.

By following these steps, you should be able to successfully install and configure BMW INPA 5.0.1 with a cheap OBD2 USB cable, enabling you to perform a wide range of diagnostic tasks on your BMW. Remember to consult online forums and communities for further assistance and specific troubleshooting for your BMW model.

Example of the INPA main screen interface after successful setup.

A typical OBD2 USB KKL adapter connected to a BMW’s OBD2 port.

Overview of the hardware components: BMW 20-pin adapter, OBD2 USB cable, and laptop.

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