A166U1UESADZI2 – Galaxy A16 5G firmware

Build A166U1UESADZI2 is a security update for the Galaxy A16 5G (SM-A166U1) on Android 16 (One UI 8). It first appeared on Samsung's servers on Oct 2, 2026 (method) and has reached 13 regions so far. It raises the bootloader bit from 9 to 10: once installed, the device no longer accepts firmware with bit 9 or lower, so a downgrade to A166U1UES9DZH1 is blocked. Samsung still serves this file.

Model
SM-A166U1
Android
Android 16
Type
Security
Bootloader bit
10
First released
Oct 2, 2026
Regions
13

Rollout timeline by region

The date each region code (CSC) first received A166U1UESADZI2, counted from the first release.

CSCRegionReleasedRolloutVersion (PDA/CSC/MODEM)
ACGUSA (C Spire)Oct 2, 2026day 0A166U1UESADZI2/A166U1OYMADZI2/A166U1UESADZI2
AIOUSA (Cricket)Oct 2, 2026day 0A166U1UESADZI2/A166U1OYMADZI2/A166U1UESADZI2
ATTUSA (AT&T)Oct 2, 2026day 0A166U1UESADZI2/A166U1OYMADZI2/A166U1UESADZI2
CCTUSA (Comcast)Oct 2, 2026day 0A166U1UESADZI2/A166U1OYMADZI2/A166U1UESADZI2
DSAUSAOct 2, 2026day 0A166U1UESADZI2/A166U1OYMADZI2/A166U1UESADZI2
DSHUSAOct 2, 2026day 0A166U1UESADZI2/A166U1OYMADZI2/A166U1UESADZI2
LRAUSA (Bluegrass)Oct 2, 2026day 0A166U1UESADZI2/A166U1OYMADZI2/A166U1UESADZI2
TMBUSA (T-Mobile)Oct 2, 2026day 0A166U1UESADZI2/A166U1OYMADZI2/A166U1UESADZI2
TMKUSA (MetroPCS)Oct 2, 2026day 0A166U1UESADZI2/A166U1OYMADZI2/A166U1UESADZI2
USCUSA (US Cellular)Oct 2, 2026day 0A166U1UESADZI2/A166U1OYMADZI2/A166U1UESADZI2
VZWUSA (Verizon)Oct 2, 2026day 0A166U1UESADZI2/A166U1OYMADZI2/A166U1UESADZI2
XAAUSA (unlocked)Oct 2, 2026day 0A166U1UESADZI2/A166U1OYMADZI2/A166U1UESADZI2
XARUSA (Cellular South)Oct 2, 2026day 0A166U1UESADZI2/A166U1OYMADZI2/A166U1UESADZI2

Download and release notes

samloader download -m SM-A166U1 -r XAA -v A166U1UESADZI2/A166U1OYMADZI2/A166U1UESADZI2

Samsung's release notes and security patch level for this update: SM-A166U1 / XAA on doc.samsungmobile.com. What each part of the build number means: decode A166U1UESADZI2.