In mid-2018, Nintendo released a hardware revision to close a critical vulnerability in the original Switch’s bootROM. This vulnerability, discovered by the hacker Katherine Temkin and named Fusée Gelée (CVE-2018-6242), allowed any Switch manufactured before July 2018 to enter Recovery Mode (RCM) and run unsigned code via a simple USB payload.
Nintendo has released multiple hardware iterations since: the "Mariko" motherboard (with longer battery life), the Switch Lite, and the OLED model. All of these are patched. The XKJ1 prefix appears on patched, original-style V2 consoles (not the Lite, not the OLED, but the red-box battery life model).
| Top number example (full serial) | Likely status | Reasoning | |----------------------------------|---------------|------------| | XKJ100000000 – XKJ1002xxxxx | Patched | Earliest Mariko units; bootrom fixed. | | XKJ1003xxxxx – XKJ1009xxxxx | Patched | Still Mariko; no unpatched models known. | | XKJ101xxxxxx and above | Patched | Confirmed patched. |
If you’ve landed here, you’re likely holding a Nintendo Switch, staring at the back of the console, and squinting at a serial number that starts with XKJ1. You’ve probably heard whispers in online forums or YouTube videos about “unpatched” Switches being valuable for homebrew, custom firmware, or emulation. Your specific question is: “Is my Switch patched if the serial number is XKJ1 and I see the word ‘TOP’ on the label?” is my switch patched xkj1 top
Let’s cut through the confusion. This article will give you a definitive answer, explain what "patched" means, decode the XKJ1 prefix, and clarify the myth around the "TOP" marking.
Yes, almost certainly. If your Nintendo Switch has a serial number starting with XKJ1, it is a patched unit. You cannot use the traditional “unpatched” Fusée Gelée exploit (the recovery mode glitch from 2018) to run custom firmware without a modchip.
However, the word "TOP" you see on the label? That has nothing to do with patched status. It refers to the manufacturing location or assembly line (likely indicating the top assembly in a specific factory). Ignore the "TOP" text—focus only on the serial prefix. In mid-2018, Nintendo released a hardware revision to
Let’s break this down so you fully understand.
Your XKJ1 top number indicates your Switch is patched. Do not buy an RCM jig expecting an unpatched exploit – it will not work. If you want homebrew or custom firmware, you will need a soldered modchip.
If your Nintendo Switch serial number starts with XKJ1, your console is 100% patched. This means it belongs to the "Mariko" hardware revision (v2), which fixed the hardware vulnerability used for easy unpatched mods. What Does "Patched" Mean? Query: XKJ1 (Top of serial number sticker) Device:
A "patched" Switch has a revised bootloader and a different Nvidia Tegra chip (the "Mariko" chip). This revision removed the RCM (Recovery Mode) exploit, a hardware-level flaw found in early v1 models that allowed users to run custom firmware (CFW) like Atmosphere using a simple RCM jig and a USB cable.
Because the fix is at the hardware level, you cannot "unpatch" it with a software update. Why XKJ1 is Always Patched
Nintendo released the v2 Switch in 2019 to improve battery life and close security loopholes.
What is the difference of a patched and unpatched nintendo switch?
Query: XKJ1 (Top of serial number sticker)
Device: Nintendo Switch (Standard model, not OLED/Lite)
Target Check: Vulnerable to Fusée Gelée (RCM exploit)?