FAQ
TL;DR: If your VAG KKL USB cable won’t show usable ports, remember it targets 4 legacy COM ports and “works only on ports com 1, com 2, com 3, com 4.” Fix by installing its USB‑serial driver so a virtual COM appears. [Elektroda, Noras14, post #16924256]
Why it matters: This FAQ helps Windows XP users quickly restore COM1–COM4 access for VAG KKL diagnostics on laptops without native serial ports.
Quick Facts
- VAG KKL over USB needs a driver that creates a virtual COM port selectable in your app. [Elektroda, Ture11, post #16917104]
- An exclamation on “USB Serial Converter” in Device Manager signals a driver problem that blocks COM creation. [Elektroda, Noras14, post #16924262]
- You choose the working COM port inside the diagnostics application, not in Device Manager. [Elektroda, Kasek21, post #16924259]
- The interface is USB-based; a physical RS‑232 port is not required on the laptop. [Elektroda, Kolobos, post #16924244]
- The reported case was solved after proper converter driver setup; the topic was closed as fixed. [Elektroda, Noras14, post #16925013]
How do I fix “COM1–COM4 missing” for a VAG KKL USB cable on Windows XP?
Install the USB‑to‑serial converter driver for the VAG KKL cable. After installation, a virtual COM port appears in Device Manager. Open your diagnostics app and select that COM port. If ports were invisible earlier, reinstalling or properly loading the converter driver is the key step. As one expert put it, “only then you will have a com port with vag,” and the user later confirmed the fix. [Elektroda, Kolobos, post #16924420]
What does the yellow exclamation on “USB Serial Converter” mean?
It indicates a driver error. Until the correct driver loads, Windows XP cannot create the virtual COM port the app needs. In the thread, the user saw an exclamation on “USB Serial Converter,” and no working COM was available for testing. Clear it by installing the proper driver for your cable’s USB‑serial chipset. [Elektroda, Noras14, post #16924262]
Do I need a physical COM port, or is USB enough?
USB is enough. VAG KKL connects via USB and relies on a driver to emulate a serial (COM) port. A built‑in RS‑232 connector is unnecessary on your laptop. After driver setup, select the created COM in your diagnostic software. [Elektroda, Kolobos, post #16924244]
Where do I select the correct COM port—Device Manager or the app?
Select it inside your diagnostics application. Device Manager just shows the port’s presence; the app must be told which COM to use. Open the app’s interface settings and choose the listed virtual COM that the driver created. [Elektroda, Kasek21, post #16924259]
What is a virtual COM port?
A virtual COM port is a software‑emulated serial port created by the USB‑to‑serial driver. When installed, it appears in Device Manager and can be chosen in apps that expect COM1–COM4. Without this driver, the app cannot talk to the cable. [Elektroda, Ture11, post #16917104]
How do I identify the right driver for my VAG KKL cable?
Read the device’s VID and PID from Device Manager and match them to the correct USB‑serial driver package. The helper in the thread explicitly asked for VID/PID to guide driver choice. Install that driver and recheck for a new COM port. [Elektroda, Kolobos, post #16924420]
My app’s port test fails on every COM. What next?
Port tests fail when the virtual COM is missing or mis‑matched. First, install the converter driver so the VAG KKL exposes a COM port. Then, pick that exact COM in the app and retest. “Only then you will have a com port with vag,” as the expert noted. [Elektroda, Kolobos, post #16924420]
Why did COM and LPT ports appear later after being missing at first?
Windows can refresh the device list after changes, reinstalls, or reboots. In the case reported, ports were initially missing but later appeared, aligning with driver or detection changes. After that, the user focused on fixing the USB converter driver. [Elektroda, Noras14, post #16924262]
What should I check in Device Manager when I see an error?
Open the device’s Properties and read the error details for the faulty USB converter. Note the VID/PID and the exact error code. Use that information to locate and install the correct driver for the cable. Then the virtual COM should appear. [Elektroda, Ture11, post #16924360]
Is the issue confirmed solved in this thread?
Yes. The original poster reported that everything works after following guidance and the topic was closed as resolved. This validates the driver‑and‑select‑COM approach for the VAG KKL on Windows XP. [Elektroda, Noras14, post #16925013]
Does VAG KKL strictly require COM1–COM4?
The user’s software required choosing from COM1 to COM4, which is common for older diagnostic tools. Ensure the driver assigns or the app accepts one of those four ports for reliable communication. That numeric limitation drove the troubleshooting here. [Elektroda, Noras14, post #16924256]
Three-step quick fix: how do I get the port working?
- In Device Manager, note the USB “Serial Converter” VID/PID and any error.
- Install the matching USB‑serial converter driver for your VAG KKL.
- Open your diagnostics app and select the newly created COM port.
[Elektroda, Kolobos, post #16924420]
Edge case: drivers installed but no COM appears—what can cause this?
A lingering Device Manager error blocks COM creation. Check Properties to see the error and confirm the VID/PID. Reinstall the correct driver, then verify the app selects the created COM. If the error persists, the cable or USB port may be faulty. [Elektroda, Ture11, post #16924360]
What did the expert say about creating the COM port?
“You need to install the drivers for the converter, only then you will have a com port with vag.” Follow that, then choose the port in your app. [Elektroda, Kolobos, post #16924420]
Can I ignore Device Manager COM entries and just configure the app?
You still need the driver so the virtual COM exists. After that, concentrate on the app’s interface settings to choose the correct COM. Without the driver, the app cannot connect. [Elektroda, Kasek21, post #16924361]
