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Restoring Your AT&T Galaxy S4 (SGH-I337): The 5.0.1 "4-File" Firmware Explained If you’ve landed here, you probably own the AT&T variant of the Samsung Galaxy S4—the SGH-I337 . And you’ve just encountered the term "5.0.1 4-file firmware." Don’t let the technical jargon scare you. This guide explains what it is, why you might need it, and how to use it safely. What is "4-File" Firmware? Most Samsung firmware comes as a single tar.md5 file . You load it into the "AP" slot of Odin and hit start. But "4-file" (or "factory" firmware) is different. It splits the operating system into four distinct parts:
BL (Bootloader): The low-level code that starts your phone. AP (PDA): The main system (Android OS, kernel, recovery). CP (Phone/Modem): Handles cell signal, Wi-Fi, Bluetooth. CSC (Consumer Software Customization): Carrier-specific settings (AT&T apps, APN settings).
Note: A true 4-file package usually includes a separate PIT file (partition layout) as well, making it technically 5 items. Why Use the 4-File Version for Android 5.0.1? Android 5.0.1 (Lollipop) was the final official update for the SGH-I337. The 4-file firmware is useful for three main reasons:
Deep Recovery: If your phone is hard-bricked (won't boot, stuck in a bootloop, or gives constant errors), the single-file firmware often fails. The 4-file version performs a full partition-level reinstall. Downgrade Prevention: The SGH-I337 has a locked bootloader with e-fuse (QFuse) technology. Flashing the 4-file package correctly prevents you from accidentally tripping "Knox Warranty Void" or bricking the device. Modem/Baseband Fix: If you have "Unknown IMEI," no service, or Wi-Fi won't turn on, reflashing just the CP file from the 4-file set can fix it without wiping your data. s4 sgh-i337 firmware 5.0 1 4file
⚠️ Critical Warning Before You Proceed This phone has a locked bootloader. You cannot downgrade to KitKat (4.4) or older once you flash 5.0.1.
Check your current Baseband version (Settings > About Phone). It likely ends in OC3 , OH3 , OK2 , or OL3 . All are Lollipop. Do NOT try to flash 4.4.2 firmware over 5.0.1. You will hard brick your device.
Where to Find Safe SGH-I337 5.0.1 4-File Firmware Do not download from random file-hosting sites. Stick with reputable sources: Restoring Your AT&T Galaxy S4 (SGH-I337): The 5
SamFW (samfw.com): Search "SGH-I337" and look for the Android 5.0.1 version. Filter for "AT&T" or "USA (AT&T)". Look for the "4 File" or "Factory Binary" tag. Updato.com (formerly Samsung-Firmware.org) – Check the "Multi-File" checkbox. XDA Developers Forum (S4 AT&T Q&A section): Search for "I337 UCUAMDB 4-file" – older threads still have working links.
File name example: I337UCUGOK2_I337ATTGOK2_I337UCUGOK2_HOME.tar.md5 (single file) vs a 4-file set will have BL_... , AP_... , CP_... , CSC_... files. How to Flash the 4-File Firmware (Step-by-Step) Prerequisites:
Samsung USB drivers installed. Odin v3.12.3 or newer (PrinceComsy’s patched Odin for locked bootloaders is even better). A Windows PC (Mac/Linux can use Heimdall, but it's trickier). Phone battery > 60%. What is "4-File" Firmware
Steps:
Extract the downloaded 4-file zip to a folder. You should see:
Restoring Your AT&T Galaxy S4 (SGH-I337): The 5.0.1 "4-File" Firmware Explained If you’ve landed here, you probably own the AT&T variant of the Samsung Galaxy S4—the SGH-I337 . And you’ve just encountered the term "5.0.1 4-file firmware." Don’t let the technical jargon scare you. This guide explains what it is, why you might need it, and how to use it safely. What is "4-File" Firmware? Most Samsung firmware comes as a single tar.md5 file . You load it into the "AP" slot of Odin and hit start. But "4-file" (or "factory" firmware) is different. It splits the operating system into four distinct parts:
BL (Bootloader): The low-level code that starts your phone. AP (PDA): The main system (Android OS, kernel, recovery). CP (Phone/Modem): Handles cell signal, Wi-Fi, Bluetooth. CSC (Consumer Software Customization): Carrier-specific settings (AT&T apps, APN settings).
Note: A true 4-file package usually includes a separate PIT file (partition layout) as well, making it technically 5 items. Why Use the 4-File Version for Android 5.0.1? Android 5.0.1 (Lollipop) was the final official update for the SGH-I337. The 4-file firmware is useful for three main reasons:
Deep Recovery: If your phone is hard-bricked (won't boot, stuck in a bootloop, or gives constant errors), the single-file firmware often fails. The 4-file version performs a full partition-level reinstall. Downgrade Prevention: The SGH-I337 has a locked bootloader with e-fuse (QFuse) technology. Flashing the 4-file package correctly prevents you from accidentally tripping "Knox Warranty Void" or bricking the device. Modem/Baseband Fix: If you have "Unknown IMEI," no service, or Wi-Fi won't turn on, reflashing just the CP file from the 4-file set can fix it without wiping your data.
⚠️ Critical Warning Before You Proceed This phone has a locked bootloader. You cannot downgrade to KitKat (4.4) or older once you flash 5.0.1.
Check your current Baseband version (Settings > About Phone). It likely ends in OC3 , OH3 , OK2 , or OL3 . All are Lollipop. Do NOT try to flash 4.4.2 firmware over 5.0.1. You will hard brick your device.
Where to Find Safe SGH-I337 5.0.1 4-File Firmware Do not download from random file-hosting sites. Stick with reputable sources:
SamFW (samfw.com): Search "SGH-I337" and look for the Android 5.0.1 version. Filter for "AT&T" or "USA (AT&T)". Look for the "4 File" or "Factory Binary" tag. Updato.com (formerly Samsung-Firmware.org) – Check the "Multi-File" checkbox. XDA Developers Forum (S4 AT&T Q&A section): Search for "I337 UCUAMDB 4-file" – older threads still have working links.
File name example: I337UCUGOK2_I337ATTGOK2_I337UCUGOK2_HOME.tar.md5 (single file) vs a 4-file set will have BL_... , AP_... , CP_... , CSC_... files. How to Flash the 4-File Firmware (Step-by-Step) Prerequisites:
Samsung USB drivers installed. Odin v3.12.3 or newer (PrinceComsy’s patched Odin for locked bootloaders is even better). A Windows PC (Mac/Linux can use Heimdall, but it's trickier). Phone battery > 60%.
Steps:
Extract the downloaded 4-file zip to a folder. You should see: